Scalable coding based video distribution

ABSTRACT

Media content coded using scalable coding techniques may be cached among a group of cache devices. Layered segments of the media content may be pre-loaded onto the cache devices, which may be located throughout a content distribution network, including a home network. The caching location of the media content may be determined based on multiple factors including a content preference associated with the group of cache devices and device capabilities. A cache controller may manage the caching of the media content.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional U.S. patentapplication No. 62/279,524, filed Jan. 15, 2016, the disclosure of whichis incorporated herein by reference in its entirety.

BACKGROUND

The landscape of video distribution may have shifted from legacy cableand/or satellite broadcasting towards on-demand content delivery.On-demand delivery may be IP based, e.g., via a fixed and/or mobilenetwork. Video consumption and its associated revenue growth may dependon user experience. Device capabilities, network accessibility, contentdiversity, and/or other factors may drive the user experience. Multicastand broadcast delivery techniques may be used to provide content withreasonable cost efficiency, but they might not meet the requirementsimposed by viewing habit changes (e.g., on-demand viewing, higherresolution, higher frame rate, multi-view, etc.). Unicast may delivercontent to an individual user directly, but it may be difficult to meetincreasing consumer demand within a reasonable timeframe. A blendedmulticast and unicast video distribution solution such as contentdistribution network (CDN) or edge caching may balance the demand andsupply to a certain degree. However, as video traffic continues toexplode (e.g., due to demand for advanced video features such as highresolution, high frame rate, HDR/WCG and multi-view), such a blendedsolution may not scale efficiently.

System, methods, and instrumentalities are described herein fordistributing media content among a group of cache devices. The mediacontent may be available at a content source (e.g., the content sourcemay include a content server, a content service, an edge server, and/orany other sources from where media content may be retrieved). The mediacontent may include one or more content objects. At least a subset ofthe content objects may have been coded using scalable codingtechniques, and may comprise a plurality of scalable layers including abase layer and an enhancement layer. The enhancement layer may have ahigher resolution and/or a wider color gamut than the base layer. Theenhancement layer may have a different format and/or represent adifferent view of a scene than the base layer. The enhancement layer maydepend on the base layer for decoding and/or playback. The group ofcache devices may include a CDN cache server, an edge cache device, ahome gateway, an end user device, and/or the like. One or more of thecache devices may be capable of decoding and playing back a contentobject. The cache devices may be connected via a network including awired or a wireless network. Content preference information associatedwith the group of cache devices may be received by a controllerconfigured to manage the distribution of the media content. The contentpreference information may include a viewing history and/or asubscription (e.g., a subscription to a TV channel or a streamingservice) associated with one or more cache devices. The controller maymonitor content availability associated with the content source anddetermine that a content object is available at the content source. Thecontroller may receive scalability information e.g., from the contentsource) associated with the content object and device propertyinformation associated with the group of cache devices. The scalabilityinformation may include resolution and/or color gamut information of thescalable layers (e.g., a base layer and/or an enhancement layer) of thecontent object available at the content source, for example. The deviceproperty information may include a display resolution, a storage size,an available network bandwidth, a caching history, a viewing habit, adecoding capability, and/or an access permission of one or more of thegroup of cache devices. The device property information may be obtainedvia device discovery (e.g., using a device discovery protocol such asUniversal Plug and Play (UPnP)).

The controller may determine that a content object available at thecontent source is relevant to at least one cache device of the group ofcache devices based on the content preference information associatedwith the group of cache devices. In an example, the determination ofrelevance may be made if a viewing history of a cache device (or a userof the cache device) indicates a preference the the content object. Inan example, the determination of relevance may be made if a subscriptionassociated with a cache device indicates a preference for the contentobject. In an example, the content object may be determined to berelevant to a cache device (e.g., a home gateway) because the cachedevice is associated with another device (e.g., an end user deviceconnected to the home gateway) that has shown a preference for thecontent object (e.g., via a viewing history of the device or asubscription to the content object associated with the device). In anexample, the content object may be determined to be relevant to a cachedevice (e.g., an edge cache server) because the cache device isassociated with another device (e.g., an end user device capable ofaccessing the edge cache server) that has shown a preference for thecontent object (e.g., via a viewing history of the device or asubscription to the content object associated with the device). Thecontroller may determine, based on the scalability informationassociated with content object that the content object includes a baselayer and an enhancement layer. The controller may select, based atleast on the scalability information associated with the content objectand the device property information associated with the group of cachedevices, a first cache device from the group of cache devices forcaching one of the base layer or enhancement layer of the contentobject. The controller may further select a second cache device from thegroup of cache devices for caching the other of the base layer orenhancement layer of the content object. For example, the controller mayselect the first cache device for caching the base layer upondetermining that the first cache device is capable of storing and/ordisplaying the base layer of the content object. The controller mayselect the second cache device for caching the enhancement layer upondetermining that the second cache device is capable of caching theenhancement layer of the content object. In an example, the group ofcache devices may include a home gateway and a plurality of end userdevices. The end user devices may be capable of connecting to the homegateway and playing back the content object. The content preferenceinformation associated with the group of cache devices may includerespective content preferences of the plurality of end user devices(e.g., viewing histories and/or subscriptions associated with one ormore of the end user devices). The controller may determine that thecontent object meets the content preferences of at least two of theplurality of end user devices and that the home gateway is capable ofstoring the base layer of the content object. The controller may selectthe home gateway to cache the base layer of the content object (e.g., sothat the base layer may be shared by the at least two of the pluralityend user devices). The controller may select one of the at least two enduser devices that is capable of storing and/or displaying theenhancement layer to cache the enhancement layer of the content object.

The group of cache devices may include a cache server located outside ahome network (e.g., on a CDN) and a home device within the home networkthat is capable of accessing the cache server. The content preferenceinformation associated with the group of cache devices may include acontent preference of the home device. The controller in such scenariosmay select the home device to cache the base layer of a content objectupon determining that the content object meets the content preference ofthe home device and that the home device is capable of caching the baselayer of the content object. The controller may select the cache serverto cache the enhancement layer of the content object (e.g., so that thehome device may stream the base layer from a local storage space and,when conditions permit, request the enhancement layer from the cacheserver). The home device described in the foregoing scenario maycomprise at least one of a home gateway or an end user device, forexample. In an example, the controller may receive device propertyinformation that includes the viewing habit of a cache device. Thecontroller may determine, based on the viewing habit, that the cachedevice has been used to stream and/or view content outside a homenetwork (e.g., via a cellular connection) at a frequency that exceeds athreshold value. The controller may decide in such cases to cache thebase layer of a relevant content object on the cache device (e.g., sothat the cache device may watch the base layer from a local storagecache while on a cellular connection and request the enhancement layerfrom a server when the cache device is connected to a home network).

The controller may receive access privilege information associated withthe media content. The access privilege may allow only certain cachedevices to access the media content, for example. Accordingly, thecontroller may select the cache devices that have access permission tothe media content to cache the base layer of the media content. Sincethe enhancement layer depends on the base layer for decoding, anunauthorized device may not be able to play back the media content ifthe device has obtained only the enhancement layer of the media content.

Upon selecting the first cache device to store the base layer of thecontent object and the second cache device to store the enhancementlayer of the content object, the controller may instruct the first andsecond cache devices to request/download their respective layers (e.g.,from the content source).

The systems, methods, and instrumentalities described herein may beimplemented on an end user device, a home gateway, a CDN server, or anyother suitable type of devices.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the embodiments disclosed herein may behad from the following description, given by way of example inconjunction with the accompanying drawings.

FIG. 1 shows an example CDN media content delivery system.

FIG. 2 shows an example of HTTP adaptive streaming.

FIG. 3 shows an example decoder architecture for the scalable videocoding extension of high efficiency video coding (SHVC).

FIG. 4 shows an example hybrid 3DTV system.

FIG. 5 shows an example of scalable video coding.

FIG. 6 shows an example CDN video distribution system.

FIG. 7 shows an example scalable coding based content distributionsystem.

FIG. 8 shows an example scheme for scalable coding based contentcaching.

FIG. 9 shows an example of intelligent cache control.

FIG. 10 shows an example of intelligent cache control using anetwork-based controller.

FIG. 11 shows an example of intelligent cache control using anetwork-based cache controller and home gateway cache.

FIG. 12 shows an example of intelligent cache control using agateway-based cache controller.

FIG. 13 shows an example of intelligent cache control using adevice-based cache controller.

FIG. 14 shows an example of video streaming from multiple sources.

FIG. 15A shows an example buffer model for a multi-source streamingscenario.

FIG. 15B shows another example buffer model for a multi-source streamingscenario.

FIG. 16A shows an example scheme for a DASH streaming device to requestdifferent layer segments from different locations.

FIG. 16B shows an example scheme for a DASH streaming device to requestdifferent segments of the same layer from different locations,

FIG. 17A depicts a diagram of an example communications system in whichone or more disclosed embodiments may be implemented.

FIG. 17B depicts a system diagram of an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 17A.

FIG. 17C depicts a system diagram of an example radio access network andan example core network that may be used within the communicationssystem illustrated in FIG. 17A.

FIG. 17D depicts a system diagram of another example radio accessnetwork and an example core network that may be used within thecommunications system illustrated in FIG. 17A.

FIG. 17E depicts a system diagram of another example radio accessnetwork and an example core network that may be used within thecommunications system illustrated in FIG. 17A.

DETAILED DESCRIPTION

A detailed description of illustrative embodiments will now be describedwith reference to the various Figures. Although this descriptionprovides a detailed example of possible implementations, it should benoted that the details are intended to be exemplary and in no way limitthe scope of the application.

Linear content distribution may be used by broadcasters, multi-systemoperators (MSOs) such as cable operators, and/or direct-broadcastsatellite television operators to deliver media content. The cost forlinear video distribution may be paid for by entities (e.g., operators,broadcasters or platforms) that produce and/or aggregate the mediacontent. Revenue may be generated via subscription and/or advertising,for example.

Linear video distribution (e.g., linear TV) may have been on thedecline. With technological innovations taking place in the videodelivery chain (e.g., video compression technologies, network deliverytechnologies, and/or network infrastructure evolution), new forms ofvideo delivery may emerge and/or grow. These new forms of video deliverymay include non-linear, multi-device, and/or internet-based videostreaming services, for example. More households may subscribe to theseservices. As video consumption moves away from a cable-centric mode andtowards a consumer-driven mode, traditional video distributionmechanisms may change.

Connected devices may change the way videos are consumed. The landscapeof connected devices may have shifted. For instance, mobile devices mayhave surpassed computers as the main form of connected devices, and mayremain so for the future. Mobile usage (e.g., data, video, voice) maybecome an essential part of people's daily life. Services related tomobile usage may drive the business of mobile network operators (MNOs).

Multicast or broadcast may use a point-to-multipoint transmissionarchitecture in which media content may be distributed centrally andreceived separately by multiple end-points. A broadcast or multicastapproach may be an efficient solution for some services (e.g., livevideo streaming) but not for others (e.g., video on-demand as it mayoccur any time after content becomes available). Unicast may use apoint-to-point transmission architecture in which an end-point (e.g.,every end-point) may make a request for certain media content and themedia content may be delivered to the end-point (e.g., separately and/ordistinctively from deliveries to other end-points).

With traditional media distribution techniques (e.g., linear TVprogramming), viewing may be passive and/or one-directional. Programschedule may be fixed ahead of time and beyond a consumer's control.Services such as cable-based video on-demand (VOD), subscription basedover-the-top (OTT) service, or apps-based video applications may allowconsumers to obtain media content at a time arid/place of their choice(e.g., anytime and/or anywhere). Video consumption through such servicesmay be driven by audience engagement and/or retention, which may bebased on individual consumers' personal content preference (e.g., whichmay be reflected through or derived from the consumer's viewing habits,viewing history, and/or service subscription).

The content preference of one consumer (e.g., which may be associatedwith the consumer's connected devices) may be different from that ofanother. For example, longer-form programs (e.g., over 30 minutes inlength) may be consumed by connected set-top-boxes (STBs), computers,and some mobile devices (e.g., tablets), while short-form content orconsumer-generated media content may be consumed by other mobile devices(e.g., mobile phones). The ability to deliver individualized mediacontent may boost video consumption and/or create opportunities forpersonalized advertising and/or purchases. Costs associated withdelivering content to consumers via unicast, however, may besignificant. The costs may arise from demands for wider bandwidth, forbetter server capacity, for higher video quality (e.g., high definition(HD) or ultra-high definition (UHD) videos), and/or the like.

A hybrid delivery architecture may be employed for media contentdistribution and/or storage. For example, multicast/broadcast may beused to deliver large, popular linear content while unicast may be usedto deliver less popular and more tailored media content. As viewinghabits change, more and more consumers may prefer personalized and/orless time-dependent experience. Demand for intelligent recommendationsfor media content may increase. Customized content delivery may bedesired. On-demand consumption may account for an increasing portion ofviewing requests. Long-form programs may move from linear TV consumptionto on-demand consumption. Unicast (e.g., unicast of longer-form mediacontent) may see increased use in video delivery.

Video distribution may use a dedicated Content Delivery Network (CDN). ACDN may include a large number of cache servers. The cache servers maybe deployed in a wide geographic area (e.g., worldwide). The cacheservers may be used to push content to the edges of the Internet. FIG. 1shows an example CDN media content delivery system. A CDN overlay may beemployed, in which one or more edge servers may be positioned in anetwork edge node. The edge node may be between an origin server ofcontent and an end user. A multicast network may be used to transportthe content from the origin server to the edge node (e.g., to one ormore edge servers located at the edge node). A unicast network may beused to reach the end user. Personalized viewing (e.g., “any content atany time” viewing) may be supported with a last-mile connection. Forexample, more popular content may be distributed using multicast to acollection of CDN caches (e.g., cache servers) simultaneously. Thecaches may store the popular content and may provide the content to anend user upon request. Server replication (e.g., having multiple serverswith premium connectivity and/or storage capacities) may increase thedeployment costs of CDNs. The introduction of new video formats and/or awider variety of user devices may contribute to the cost increase. Atleast in some cases, CDNs and edge servers might not be able to reachthe last mile of the Internet.

Adaptive video streaming over HTTP may be utilized to deliver mediacontent. Adaptive video formats may include, for example, dynamicadaptive streaming over HTTP (DASH). With adaptive streaming, multiplerepresentations of the same content may be generated. A representationmay be segmented into smaller chunks or segments. The chunks or segmentsmay have different durations (e.g., between 2 to 10 seconds). When astreaming device (e.g., which may be a cache device, including anend-user device) requests media content from a server, the server maysend a description of the media content (e.g., via a media presentationdescription (MPD) manifest file) to the streaming device. The MPD filemay inform the streaming device about the bitrates of the requestedmedia content, for example. The MPD file may provide universal resourcelinks (URLs) for downloading the media content. The streaming device mayrequest one or more video segments with a particular bitrate (e.g., ahigh or enhanced bitrate, a low or base rate, a medium rate, etc.).Based on the time it may take to receive a segment, the streaming devicemay assess various conditions (e.g., network and/or streaming deviceconditions), and may select the next segment according to the MPD and/orthe assessed conditions. For example, the selection may be made uponconsideration of quality requirements, network bandwidth, devicecapabilities and/or the like.

FIG. 2 illustrates an example of HTTP-based adaptive streaming of mediacontent. The media content may have been divided into multiple segmentseach coded into one or more representations (e.g., Rep. 1, Rep. 2, andRep. 3) at different bitrates (e.g., Rep. 3 may have the highestquality, Rep. 2 may have a medium quality, and Rep. 1 may have thelowest quality). A streaming device (e.g., such as a smart TV 502) mayrequest the media content from an origin server 504 over a network(e.g., such as the Internet). The streaming device 502 may request aspecific representation of the media content based network conditions,the streaming device's capabilities, and/or various otherconditions/factors. Higher quality representations of the media content(e.g., such as the Rep. 2 and Rep. 3 segments) may be requested andtransmitted over the network when network bandwidth is sufficient. Lowerquality representations of the media content (e.g., such as the Rep. 1segments) may be requested and transmitted over the network when networkbandwidth is low.

Table 1 shows example video stream files each containing the same mediacontent coded at different bitrates.

TABLE 1 Example Video Stream Files Containing Video Content of DifferentBitrates Video Playback Rate (kbps) File Name Desktop Client 23515304768.imsv 375 22630482.imsv 560 20693663.ismv 750 17864652.ismv 105017091067.ismv 1750 18266773.ismv 2350 39219201.ismv 3000 41121933.ismvSmart-phone Client 110 14705760.imsv 182 14986798.imsv 257 15723334.ismv506 15411523.ismv

The bitrate at which video content is encoded may affect distribution ofthe video content. Video codec may be used to compress a digital videosignal. Through compression, resource requirements (e.g., storage and/ortransmission bandwidth requirements) for distributing the video signalmay be lowered. Table 2 shows example average speeds for streaming videocontent of different resolutions and/or coded with different videocoding standards.

TABLE 2 Example Average Video Streaming Speeds Average Speeds DefinitionApproximate Bitrate (Mb/s) SD MPEG 2 4.0 SD MPED 4 1.5 HD MPEG 2 10.0 HDMPEG 4 3.5 UHD MPEG-4 28.0 UHD HEVC 15.0

High Efficiency Video Coding (HEVC) and/or its extensions may be used tocode multiple video formats. The scalable video coding extension of HEVC(SHVC) may be used to code (e.g., via scalable coding) video contentinto multiple layers. The layers (e.g., a base layer (BL) and one ormore enhancement layers (ELs)) may correspond to differentrepresentations of the video content. The layers may have differentspatial resolutions, different temporal frame rates, differentqualities, different color spaces, and/or the like. For example, a baselayer representation may be coded at a base bitrate and an enhancementlayer representation may be coded at an enhanced bitrate that is higherthan the base bitrate. The enhancement layer representation may dependon the base layer representation for decoding and playback.

FIG. 3 shows an example SHVC decoder architecture 300. An inter-layerreference picture may be used in SHVC as an additional reference pictureto predict an enhancement layer representation. SHVC coding tools may beused at the slice level and above. One or more existing single layerHEVC implementations may be re-used in SHVC. Interlayer processing(e.g., as shown in FIG. 3) may include a resampling process for spatialand bit depth scalability, and/or a color mapping process for colorgamut scalability (CGS).

The performance of SHVC may be evaluated, Table 3 shows exampleperformance comparison between SHVC (e.g., for spatial andSignal-to-Noise-Ratio (SNR) scalability) and simulcast when two layersare coded independently. For random access, which is a codingconfiguration used in certain video entertainment applications, SHVC mayachieve an overall rate reduction of 16.5% to 27% at the same peaksignal-to-noise ratio (PSNR) when both base layer and enhancement layerbit rates are considered.

TABLE 3 SHVC Performance vs. Simulcast Performance Configuration Anchor2× (%) 1.5× (%) SNR ( % ) Random access SHVC versus 16.5 27.0 20.9simulcast SHVC EL versus 26.0 47.6 31.4 single-layer EL Low delay SHVCversus 10.3 21.5 12.5 simulcast SHVC EL versus 16.8 39.3 19.5single-layer EL

Scalable video coding may enable layered services to support thetransmission and decoding of a partial bitstream. Differentrepresentations of the same content may be delivered to differentdevices based on their capabilities and reception conditions. Further,scalable streams may reduce the overall cost of storing a catalog (e.g.,an entire catalog) in multiple titrates, and/or the amount of upstreamtraffic generated from keeping CDN and edge caching content up to date.

FIG. 4 shows an example Hybrid 3DTV system (e.g., with SHVC servicemode). The addition of SHVC service mode may enable service flexibilitybased on SHVC options. In the example, a high definition (HD) right viewmay be coded as a base layer. An ultra HD (UHD) left view may be codedas an enhancement layer, for example, with a conventional SHVC encoder.The base layer bitstream (e.g., HD right view) may be delivered (e.g.,via QPSK or 16 QAM) to a mobile device (e.g., a mobile device thatsupports HD services). The enhancement layer UHD left view may bedelivered (e.g., via 256 QAM) to a UHDTV (e.g., a UHDTV that supports 2DUHD services). The enhancement layer UHD left view may depend on thebase layer for decoding and playing back. The synthesized right view andleft view may be delivered to a UHD 3DTV. Such layered broadcasting of2D and 3D content may support UHDTV, UHD 3DTV and/or mobile HDTV, e.g.,within a RF channel.

Video coding standards beyond HEVC may aim at further compressionefficiency (e.g., on top of HEVC). Another goal may be to alleviatenetwork congestion in fixed and/or mobile networks. Various aspects ofvideo formats, such as high resolution, high frame rate (HFR), high bitdepths, high dynamic range, wide color gamut space and/or multipleviews, may be considered. The quality of video content may reach a levelcloser to the capacities of the human vision. UHD formats may defineparameters in multiple aspects of a video signal. For example, inaddition to higher spatial resolutions of 4 k and 8 k image samplesand/or higher frame rate of up to 120 HZ, the sample bit depths may beup to 12 bits to provide high dynamic range (HDR) support. A wider colorgamut (WCG) may be used for the rendering of colors.Stereoscopic/multi-view or free-view video may become a relevant format.A scalable coding structure may be designed to support a diverse set ofvideo formats. For example, a scalable coding architecture similar tothat of the SHVC may be applied for coding standard development, withadditional coding tools targeting different video formats.

FIG. 5 shows an example of scalable video coding. Using scalable coding,media content may be coded into multiple formats including, for example,high resolution, high frame rate, multi-view, high bit-depth, highdynamic range (HDR), and/or wider color gamut (WCG). Each format mayproduce a unique viewing experience. Different mixtures of formats maybe used to represent the video content at various bitrates. For example,a mixture of SD/30 fps/single view/4:2:0/8 bit/BT.709 may be used torepresent the video content at low bitrates, a mixture of 1080 p/60fps/single view/4:2:2/10 bit/p3/SDR may be used to represent the videocontent at medium bitrates, and a mixture of 4 k1120fps/multi-view/4:2:2/12bit/BT2020/HDR may be used to represent the videocontent at high bitrates. Formats with enhanced viewing features (e.g.,in different dimensions) may share a basic common format (e.g., SD/30fps/single view/4:2:0/8bit/BT.709). Such a basic common format may becoded as a base layer.

With scalable video coding, a video format may be coded on top of aconventional video format. The correlation among multiple formats of thesame content may be explored during scalable coding. A layered codingstructure may be used. A single scalable bitstream of a catalog may bestored on a content server (e.g., which may be an example of a contentsource referred to herein). Different layers of the scalable bitstreammay be extracted (e.g., be extracted as the bitstream is being requestedor retrieved). The extracted layers may be delivered to multipleconnected devices, for example, during an adaptive streaming session.The connected devices may have different capabilities and/or servicesubscriptions.

With scalable coding techniques, adaptive streaming of video content maybe possible. Different layers of the video content may have differentrandom access frequencies. Various techniques may be used to speed upadaptation and/or to reduce re-buffering. Examples of these techniquesmay include fast tune-in, fast switch-up, and/or fast switch-down.

As content servers and/or storage resources are centralized in largeInternet exchanges and/or data centers, the edge of the Internet mayexpand and more traffic may originate from edge caches instead fromlarge data centers. Pushing content to connected devices may reduce thetraffic between edge caches and end users. As described herein, nextgeneration video coding standard may support multiple video formats. Awide range of enhanced video content may be covered. Efficientcompression techniques may become available. Multiple copies of the samevideo content (e.g., copies of different resolutions, bitrates, and/orenhancement features) may be stored on edge servers. The copies may beused by the edge servers to fulfill client requests based on theclient's capabilities, network conditions, subscription plans, and/orother factors. Enhanced video features, such as high resolution, highframe rate, high hit-depth, and/or the like, may increase the number ofcopies (e.g., copies of the same or different content) of video streamsthat need to be stored on a CDN or edge server. Operational cost forservice providers may increase.

When the same video content is coded into multiple representations atdifferent bitrates and/or with different video formats (e.g., in ahierarchical CDN topology), high bitrate video segments may be stored ona remote server while low bitrate video segments may be stored in anedge cache. When a streaming device requests particular video content,some segments of the content may be provided directly from the edgecache to the streaming device. The streaming device may assess a networkcondition (e.g., connection speed between the edge cache and thestreaming device) based on how the requested video content are beingdelivered. If the connection speed is sufficient, the streaming devicemay request more high-bitrate segments. Such high-bitrate segments maybe stored on a remote server and may be delivered from that serverdirectly. When the connection speed between the remote server and thestreaming device becomes insufficient, the streaming device may requesta reduced bitrate representation of the content, and may be directedback to the edge cache to retrieve the representation. As such, thestreaming device may engage in a process in which the streaming devicemay switch between an edge cache and a remote server to retrieve videosegments of different qualities.

With scalable video coding, a streaming device may be able to receivelower resolution content (e.g., one or more base layer segments)consistently since such content may be retrieved from an edge cache(e.g., even if network speed is low). As more network bandwidth becomesavailable, the streaming device may request higher resolution content(e.g., one or more enhancement layer segments) from a server while stillreceiving base layer segments from the edge cache. When connection speedbetween the server and the streaming device becomes insufficient, thestreaming device may cease retrieving enhancement layer segments fromthe server, and may still retrieve base layer segments from the edgecache. This way, the streaming device may avoid having to switch betweenthe server and the edge cache under fluctuating network conditions.

Scalable video coding techniques may keep infrastructure costs (e.g.,costs associated with edge servers) under control. Streaming featuresthat may be enabled by scalable video coding, such as quick bandwidthadaptation and re-buffering time reduction, may improve consumerexperience on various devices. Video consumption may be driven higher.

FIG. 6 shows an example of a hierarchical CDN 600. A content provider oraggregator may distribute and/or replicate media content onto thehierarchical CDN 600 (e.g., via broadcast and/or multicast from acontent source). The content may be coded into multiple representations(e.g., rep1, rep2, and rep3) with different qualities. Copies of thecontent may be replicated to one or more edge cache servers. The edgecache servers may serve their content to end users (e.g., via videoon-demand). The service may be provided via unicast or broadcast, forexample. The service may be carried over a fixed network to a home, awireless network to mobile devices, or a combination of fixed and mobilenetworks.

Commonly shared lower resolution video content (e.g., such as qHD(960×540) resolution videos coded at 256 kbps) may be cached atlocations close to an end user. Such locations may be within a homenetwork, such as a home gateway and/or an end user device (e.g., thelocation may be local storage space on a WTRU, as described herein).Caching at these locations may be possible because the low resolutioncontent may be accommodated with limited storage space and/or may becompatible with a wide range of end user devices (e.g., the end userdevices may include computers, TVs, or WTRUs as described herein).Medium resolution content, such as 1080 p resolution enhancement layerstreams coded at a medium bitrate, may be moved to a CDN or edge serversthat serve metropolitan areas. High resolution content, such as 1080 Por 4K enhancement layer streams coded at a high bitrate, may bedistributed based on factors that may affect the distribution (e.g., thenumber of premium subscribers and/or their locations).

FIG. 7 shows an example scalable coding based content distributionsystem 700. Different representations of scalable video content may bedistributed across the system 700 in a hierarchical manner. The videocontent may include one more content objects (e.g., TV shows, movies,video clips, etc.). Each content object may be coded into multiplerepresentations of different qualities. For example, a firstrepresentation of a content object may be a based layer (BL)representation coded at a base bitrate, a second representation of thecontent object may be an enhancement layer (ELI) representation coded ata medium bitrate that is higher than the base bitrate, and a thirdrepresentation of the content object may be another enhancement layer(ELI) representation coded at a high bitrate that is higher than themedium bitrate. The content distribution system 700 may include acontent server (e.g., which may an example of a content source referredto herein) on which the video content may originally reside. The contentserver may belong to a content provider or aggregator, for example. Thecontent distribution system 700 may include one or more CDN servers,which may be connected to the content server through a backbone network.The content distribution system 700 may include one or more edge cachedevices located at the edges of IP networks. The edge cache devices maybe connected to the CDN servers via the IP networks. The edge cachedevices may be accessible to home devices (e.g., via a fixed network) orto mobile devices (e.g., via a mobile network).

A determination may be made (e.g., by a cache controller) to map thevideo content to the various devices in the content distribution system700 (e.g., to decide which content objects and/or representations shouldbe cached on which devices, including end user devices and homegateways). Various considerations may be taken into account in thedetermination, including, for example, an end user device's storagecapacity or the likelihood that certain cached content may not bewatched (e.g., which may result in storage and/or network bandwidthwaste). Since content cached on an end user device or a home gateway mayserve a group of end users (e.g., end users associated with or served bythe end user device or home gateway), the content may be selected and/orpersonalized for the group of end users.

A caching strategy for scalable media content may be set according tothe content preference (e.g., which may be reflected through or derivedfrom viewing habits, viewing history, and/or service subscription) of anend user. The content preference of the end user may be associated witha device of the end user. The content preference may be related to theend user's gender, age, religion, education, culture background, and/orvarious other characteristics. Content consumption analysis may beperformed to determine which video programs should be cached. Thecaching strategy may take into account the end user's viewing history.The caching strategy may be based on the end user's time zone and/orlocation. Based on these and other user information, the media contentto be cached on an end user device or a home gateway, and/or the time todownload the media content may be determined. For example, a controller(e.g., which may comprise software programs and/or hardware components)may be provided for determining which content should be cached. Thecontroller may reside on a device within a home network (e.g., on an enduser device, a home gateway, etc.) and/or a network entity outside thehome network (e.g., such as a CDN server or a content server, which mayconnected via the Internet). The controller may monitor or may beprovided with the viewing history of one or more end users associatedwith the end user device, the home gateway, and/or the network entity.Based on the viewing history, the controller may predictively selectmedia content for local caching. For example, if a particular end userdevice frequently watches the latest episodes of a particular news showor a television series (e.g., within a certain time frame of the initialrelease of such episodes), the controller may monitor those programs fornew episodes. When a new episode is detected, the controller may requestthat the content of the new episode he cached on the end user device.The controller may request a specific representation of the content(e.g., the controller may request that base layer segments of thecontent be cached on the end user device, or that enhancement layersegments of the content be cached on the end user device).

A home gateway may be associated with a group of end user devices. Thecontroller described herein may monitor what media content is selectedfor viewing by the group of end user devices and/or what content isserved to such end user devices through the home gateway. The controllermay monitor the viewing history (e.g., the aggregate viewing history) ofthe group of end user devices associated with the home gateway. Forexample, if the controller determines that the latest three episodes ofa particular TV show have been commonly requested and/or played by thegroup of end user devices, the controller may request that media contentfor the latest three episodes of the TV show he cached in the homegateway. For example, the controller may request that one or morescalable base layer segments of the media content be cached in the homegateway, or that one or more scalable enhancement layer segments of themedia content be cached in the home gateway. The controller may monitorthe TV show for new episodes. The controller may manage the availablecache storage on the home gateway. For example, older episodes of the TVshow may be deleted when storage room runs low (e.g., falling below athreshold). New episodes may be requested and/or cached when morestorage room becomes available.

The controller described herein may adaptively determine whether tocache media content on an end user device or on a home gateway. Thedetermination may be made based on various factors. For example, thedetermination may be made based on whether the media content in questionis historically watched on a single device or across multiple devicesserved by a common home gateway. In the former case, the software mayrequest that the media content be cached on the single device. In thelatter case, the software may request that the media content be cachedin the home gateway. The storage available within the home network maybe managed so that content may be placed where it is likely to beviewed.

The controller described herein may select or personalize a portion ofan existing edge cache or CDN outside a home network. The selected orpersonalized portion may be used as a dedicated cache for a particularend user. The dedicated cache capacity may be expanded to store moreprograms. Content replication may be carried out locally withoutdelivery to the end user. For example, the content replication may occurinside the edge cache or CDN. The personalized cache may be physicallyallocated or may be virtually mapped to existing cache.

Other factors such as explicitly provided consumer preferences orknowledge about the consumer (e.g., such as age, gender, religion,educational level, or cultural background) may be considered by thecontroller.

Different servers may be dedicated to store different representations ofmedia content. The representations may have different characteristicsincluding format, resolution, etc. For example, an edge cache server maybe configured to store base layer content shared by multiple end users.A first group of CDN middle servers (e.g., located between the edgecache server and the origin content server) may store enhancement layercontent with higher spatial resolution. A second group of CDN middleservers may be configured to store enhancement layer content withmulti-view. A third group of CDN middle servers may be configured tostore enhancement layer content with wider color gamut.

As shown in FIG. 7, layered media content may be cached on home gatewaysor end user devices. The scalable media content may be distributed tothose cache devices (e.g., the home gateways and/or end user devices)over a network (e.g., an existing coaxial cable network, a broadband IPnetwork, a wireless network, etc.). The content may be distributed usingmulticast or broadcast. The cache devices may support content sharingamong end users of a same local network such as a home network. Contentexchange among the cache devices (e.g., among home gateways and/or enduser devices) may utilize multicast, unicast, peer-to-peer (P2P)delivery (e.g., between a home gateway and an end user device, orbetween end user devices), and/or the like. The sharing/exchange mayallow CDNs to offload data traffic from last mile connections to homenetworks. The offloading may occur during off peak hours to alleviatenetwork congestion.

FIG. 8 shows an example scalable coding content caching scheme. Mediacontent may be coded into one or more representations (e.g., therepresentations may have different resolutions and/or formats, asdescribed herein). The representations may include a base layerrepresentation (e.g., of low quality) and one or more enhancement layerrepresentations (e.g., of medium and high qualities). Therepresentations may be distributed from a cable headend, a MNO, a CDNserver, and/or the like.

The base layer representation and/or the one or more enhancement layerrepresentations may be cached on devices located near an end user. Thesedevices may include, for example, devices located within a home networksuch as an end user device (e.g., a WTRU described herein), and/or ahome gateway. Multicast or broadcast may be utilized to distribute thecontent to the devices. The multicast/broadcast distribution may occurduring off-peak hours (e.g., late night to dawn). The caching scheme mayfacilitate uninterrupted viewing from time-shifted video applicationssuch as indoor streaming, on-the-road viewing (e.g., via a wirelessconnection), etc.

In addition to or in lieu of storing the base layer representation on alocal device, the base layer representation may be stored on an edgecache server and be delivered to one or more end user devices at viewingtime. Media content may be accessed this way without being replicated(e.g., without being replicated to multiple cache devices). Forconsumers subscribing to high fidelity services, the enhancement layerrepresentation cached in a home gateway and/or an end user device (e.g.,during off-peak time) may depend on a corresponding base layerrepresentation for decoding and/or playback (e.g., the enhancementrepresentation may not be decoded and displayed until it is added on topof the base layer representation). As such, content protection may beaccomplished via the caching scheme described herein. A controller mayreceive information/communication regarding the copyrights of certainmedia content, and selectively cache the base layer and enhancementlayer representations of the media content so that unauthorized use ofthe media content may be prevented. For example, caching of base layerand enhancement layer representations of media content may be arrangedso that an unauthorized user having access to locally cached enhancementlayer representations may not be able to play back the media contentwithout also having access to the base layer representation of the mediacontent. The base layer representation may be cached in the network, andaccess to the base layer representation may require authentication, forexample. The content protection techniques described herein may be usedin addition to or in lieu of other forms of content protection such asencryption or content scrambling.

End users may pre-load media content (e.g., for road trips or offlineviewing). With scalable coding, a cache controller may select a numberof layers to deliver to a local cache ahead of the viewing time based onnetwork conditions (e.g., available bandwidth), estimated offline time,and/or other device- or user-related information. This may beillustrated in the example below.

Media content (e.g., a content object) may be coded into multiplesegments each having one or more layers. The layered media content maybe delivered (e.g., sequentially delivered) from a server to an end userdevice based on the condition specified in (1) below. In (1), S_(ij) mayrepresent the size of a j-th segment of an i-th layer media stream, Tmay represent the estimated time an end user device will remainconnected with a home network, and BW may represent the average downloadbandwidth of the network (e.g., which may be a Wi-Fi network or abroadband network). According to (1), m segments of n layers of thecontent may be delivered if the total size of those segments/layers isless than or equal to the total amount of bandwidth available within thetime period T (e.g., represented by BW*T). After the delivery, the enduser may have at least the base layer content pre-loaded, and may playback the media content later without a network connection.

Σ_(i=0) ^(n)Σ_(j=0) ^(m) S _(i,j)≤BW*T   (1)

If a second network is available (e.g., a 3G/4G wireless network) forreal-time streaming, enhancement layer content may be delivered via thesecond network to provide high quality video presentation to the enduser.

As described herein, home gateways and/or local devices may provide anoverlay network on top of a content delivery network. A layer-basedand/or collaborative caching strategy may off-load network traffic,e.g., by leveraging local storage and/or upload capacities. Resourceusage at the network and/or streaming devices may be configured tocontrol the overall storage/distribution cost and/or to improveperformance throughout the network (e.g., in the last mile of thenetwork). Various algorithms may be used (e.g., a “push” strategy may beimplemented, as described herein) to place content among local storagedevices. Future requests from end users may be predicted by analyzingthe users' viewing habits and/or other personal traits.

Media content demanded by a mass audience may be delivered using amobile network such as a LTE network. The mobile network may allowoperators (MNOs) to offer different services based on the service type(e.g., live or non-real time), location (e.g., venue-specific, local,regional, or national), quality (e.g., bitrate, QoS), time, and/orvarious other factors. Scalable base layer content may be pushed tomobile devices via LTE broadcast (e.g., during off-peak hours to offloadstreaming traffic). For example, with high viewership movies, TVprograms, and/or live events, LTE broadcast may be used to deliver baselayer single-view, low frame rate, and/or standard dynamic rangecontent. Enhanced features such as multi-view, HDR and or WCGenhancement content may be delivered (e.g. In the form of one or moreenhancement layers) via unicast.

Subscribers may act as hosts and offer local cache space (e.g., localgateways or routers with storage capability) to share with devices inthe surrounding area. Authorization from the hosts may be required toaccess the shared cache. For example, a school or library may serve as ahost and cache local news or public programs on its gateways. Authorizedstudents of the school and/or patrons of the library may fetch thecached content from the school or library's gateways (e.g., as opposedto streaming the content from a CDN or edge servers). The fetching maybe performed via device-to-device or peer-to-peer communication, forexample. As another example, relatives and friends of a host user wholive close to the host user and/or who share the host user's viewinginterests may request and obtain permission from the host user to streamcontent from a device or gateway of the host user that has beendedicated as shared local cache.

Base layer content may be delivered via broadcast or multicast. In suchcases, the base layer content might not be provided via on-demandservices. TV programs such as news reports and weather forecasts maybecome outdated quickly (e.g., losing their popularity when a morerecent report or forecast becomes available). Thus, it may not becost-effective to deliver these types of TV programs to on-demandcustomers via unicast, or to frequently replicate newly released contentof the programs on edge servers for time-shifted viewing. Rather, theprograms may be pushed to local cache (e.g., via LTE broadcast). Cachereplacement policies may be employed to manage the local cache. Forexample, the policies may be used to determine what content should bereplaced when the local cache becomes full. Cache replacement policiessuch as Least Recently Used (LRU) and/or Least Frequently Used (LFU) maybe used to schedule the replacement of locally cached content. A storagearea allocated to cache a certain program may be periodically updatedwith new content. If a first viewer requests a scheduled program and asecond viewer in a neighboring area is already watching the programand/or has cached the program on a local device, the first viewer maystream the program directly from the second viewer's local device.

FIG. 9 shows an example of intelligent cache control. The control may beexercised by an intelligent cache controller to allocate differentscalable layers of the same or different content objects on differentcache devices. The cache devices may include end user devices such asmobile phones, tablets, network connected televisions, set top boxes,media player devices, gaining consoles, portable gaining devices,personal computers, and/or the like. The cache devices may include othertypes of WTRUs as described herein. The devices may be capable ofplaying scalable media content and/or storing the scalable mediacontent. In some cases (e.g., a degenerate case), an end user device maybe capable of playing non-scalable media content (e.g., onlynon-scalable media content) and/or storing the non-scalable mediacontent.

The cache controller may control caching in a mixture of end userdevices. Some of these end user devices may support playback of scalablemedia content. Some of these end user devices may support playback ofnon-scalable media content (e.g., only non-scalable media content). Someof these end user devices may be cache-only devices that do not decodeand play media (e.g., such as a home gateway). Some of these end userdevices may be capable of receiving media content via a home network.For example, the media content may be received (e.g., for caching and/orfor real-time playback) via a home gateway.

The cache controller may control caching in devices outside a homenetwork (e.g., in CDN cache and/or edge cache). The cache controller mayhave knowledge (e.g., may acquire knowledge) of content objects and/orscalable layers of the content objects that may be available (e.g., onthe outside caching devices). The cache controller may use suchknowledge to decide which content objects and/or scalable layers shouldbe cached on which devices (e.g., within a home network or a CDN). Thecache controller may direct a home network device to a nearby outsidecache when instructing the home network device to download mediacontent. For example, the cache controller may direct the home networkdevice to a neighboring outside cache if certain content objects orspecific scalable layers of the content objects are available in thatoutside cache.

As illustrated in FIG. 9, the cache controller may obtain a list ofdevices for caching purposes. The list of devices may include devicesavailable in a home network. The list of devices may include end userdevices. For example, the list of devices may include devices capable ofdecoding and playing media content, and/or caching media content (e.g.,capable of caching one or more scalable layers of one or more contentobjects). The list of devices may include a home gateway with cachingcapabilities. The list of devices may include devices such as routers,or media storage/media server devices with caching abilities and/oraccessible to other end user devices in the home network. Moregenerally, the list of devices may include a device that is capable ofcaching media content and/or that is capable of decoding and playingmedia content.

The list of devices may be derived in various ways. In an example, adevice discovery protocol such as Universal Plug and Play (UPnP) may beused to discover the devices in a home network. The cache controllerand/or a central device such as a home gateway or media server that isnot acting as the cache controller) in the home network may broadcast asignal into the home network asking devices to respond and identifythemselves. In an example, the list of devices may be discovered througha semi-automatic or manual registration process. The registrationprocess may be initiated by a user or owner of the home network. In anexample implementation, a device discovery procedure may be carried outto identify potential devices. A user may choose (e.g., through a userinterface) which devices are allowed to cache content under thedirection of the cache controller. The user may install a clientapplication or other suitable software on devices that may participatein the aforementioned controlled caching system. The client applicationmay register with the cache controller, which may reside locally on ahome device (e.g., on a home gateway), or outside the home network(e.g., on the Internet or another network as described herein). Theclient application may communicate with the cache controller to, forexample, receive and execute caching instructions transmitted by thecache controller. The instructions may specify, for example, the timeand location at which the cache devices may retrieve media content,and/or the specific content objects to be retrieved.

The list of devices may be constructed by the cache controller. The listof device may be constructed by another device and then communicated(e.g., at once or in pieces) to the cache controller. In an example, ahome gateway or a media server in the home network may use a devicediscovery protocol within the home network to determine what devices areavailable in the home network, and the home gateway or media server maycommunicate this information (e.g., as a list of such devices) to thecache controller (e.g., a cache controller residing outside the homenetwork).

The cache controller may obtain device characteristics and/or deviceproperty information (e.g., capability information) for the variousdevices on the device list. In an example, a device (e.g., an end userdevice or another device with caching capabilities) may send propertyinformation (e.g., capability information) to the cache controller. Theproperty information (e.g., capability information) may include, forexample, caching capability, total storage size (e.g., cache size), thesize of currently available cache space, types of scalable layer thedevice is capable of decoding, types of scalable layer the device iswilling to cache, information about supported codecs on the device,profiles and/or levels which the device is capable of decoding and/orusing, a maximum display resolution supportable by the device, amobility type (e.g., whether the device is mobile or fixed), a list ofnetwork connection types and/or connection speeds the device is capableof supporting, statistics on how often the device is available in thehome network, and/or the like. In certain scenarios (e.g., when thecache device is a home gateway), the property information (e.g.,capability information) may include an indication of which devices(e.g., which end user devices) can access content from the cache device,an indication of whether or how often such devices have accessed contentfrom the cache device in the past, and/or an indication of how often thecache device has detected the other devices in the home network.Capability information and other device characteristics may beidentified using a signaling protocol (e.g., an explicit signalingprotocol). Some device characteristics may be inferred based on anidentifier of the device—for example, a model number of a smart TV maybe reported or identified, and fixed characteristics (e.g., supportedcodecs/profiles levels, display resolution, and other characteristicstied to that model number) may be inferred by the cache controller,e.g., using a database that maps device identifiers such as modelnumbers to characteristics of the identified devices.

The cache controller may monitor and/or obtain program availability(e.g., from a content source, which may be associated with a contentprovider). Program availability may indicate what programs (e.g., mediaobjects representing shows, episodes, shorts, movies, news casts, etc.)are available and may be requested, retrieved, and/or played by devicesin a home network. The program availability may take the form of aprogram guide, for example. The program guide may indicate metadata foran available program. The metadata may indicate, for example, a programtitle, program description, coding formats, quality matrix, searchabletags and/or classifiers that describe the content of the program, aseries relationship wherein multiple programs may form episodes in aseries, a location from which the program or a manifest for the programmay be retrieved, and/or the like. The program availability informationmay be updated periodically, for example, as new programs becomeavailable and/or as older programs become unavailable. The cachecontroller may, for example, monitor and/or request program availabilityupdates from the one or more content sources (e.g., which may beassociated with one or more content providers) via network requests(e.g., HTTP or other suitable protocol).

The cache controller may obtain an end user's content preference (e.g.,which may be reflected through or derived from the end user's viewinghabits, viewing history, and/or service subscription). Such informationmay indicate programs, program series, types of the programs (e.g.,metadata tags or classifiers descriptive of such program types) that theuser has viewed in the past, or which the user has indicated a desire toview in the future, and/or the like. The content preference may includeprograms the user has specifically placed in a queue or flagged to watchlater. The content preference may include one or more recommendationsfrom a content provider, which the content provider may be displaying orplanning to display to the user (e.g., “These titles are recommended foryou” or “These titles are related to Movie X”). The content preferencemay indicate to the cache controller a number of programs or series ofprograms that the user is likely to watch in the future, or that theuser would have easy access to play within a user interface (UI) (e.g.,an UI displayed by the content provider).

The content preference described herein may be specific to an end userand/or associated with a specific device (e.g., an end user device onwhich media content is watched, possibly by more than one user). Thecontent preference may indicate a correspondence between the previouslyviewed, preferred, recommended or queued content and the user and/ordevice to which such content is relevant. The content preferences mayindicate which users typically watch content on which devices.

The content preference described herein may be obtained from end userdevices. For example, an end user device may track what content iswatched on the device, what content series are watched on the device,what types of content are typically watched on the device, what specificpreferences the user has indicated (e.g., in an explicit survey, or viarating content after viewing), and/or the like. The end user device mayreport such information to the cache controller, e.g., directly or viaan intermediate device such as a home gateway. The content preferencedescribed herein may be provided by (e.g., obtained from) a contentservice that tracks content watched by certain users or on certaindevices. For example, a content streaming service may track whatcontent, content series, or types of content are watched by a particularuser (or within a user profile) or on a particular device. The contentservice may track specific preferences the user has indicated (e.g., inan explicit survey, or via rating content after viewing). The contentservice may provide such information to the cache controller. The cachecontroller may use such information to make caching decisions for thevarious devices.

The cache controller may determine the relevance of available contentobjects to various devices (e.g., cache devices, including devices withviewing capabilities). For example, the cache controller may determine(e.g., based on content preference associated with an end user and/or anend user device) which content objects are likely to be relevant to anend user device within a time period. This may be illustrated by thefollowing examples. If a user habitually watches new episodes of aseries on a particular tablet device, the cache controller may determinethat new episodes of the series may be relevant to the tablet device. Ifa particular mobile phone and an HDTV are both seen to be used to watcha particular financial news program, the cache controller may determinethat the latest episode of the financial news program may be relevant toboth the mobile phone and the HDTV. If movies placed in the “watchlater” queue of a particular content service are frequently viewed usinga particular UHD television, the cache controller may determine that themovies in the “watch later” queue may be relevant to the UHD television.More generally, the cache controller may determine the relevance ofavailable content objects to users and/or devices. The cache controllermay identify a relative importance of such content for the users and/ordevices. Importance may be judged based on a number of criteriaincluding, for example, the frequency of viewing a particular show orcontent type in the past on a given device, a relative rating of theshow or content type which a user has given after watching such contentin the past, a position within the “watch later” queue, and/or the like.

The cache controller may determine the availability of media content(e.g., which scalable layers and/or scalable layer types are availablefor a content object). For example, the cache controller may determinewhich scalable layers and/or scalable layer types are available for acontent object that is relevant to a streaming device. The cachecontroller may request such information from a content source e.g.,which may provide a content service). The information may have beenbundled with the program availability information already received. Toillustrate, consider a case where the cache controller has determinedthat the latest episode of a show called “Checkmate” is relevant to amobile phone, a tablet device, and a 4K UHD TV in a home network. Thecache controller may request from the content service information aboutthe scalable layers available for this program, or the cache controllermay look up the information in an already received program guide (e.g.,which may be also from the content service). The cache controller mayrequest a manifest associated with the program (e.g., a DASH MPD file),and the manifest may contain a listing of the available scalable layersand/or the scalability type for one or more of the layers.

The cache controller may determine the relevance of the availablescalable layers to various devices, cache devices, including deviceswith viewing capabilities). For example, if a content object a TVprogram) is determined to be relevant to the devices (e.g., as describedherein), the cache controller may further determine the relevance of theavailable scalable layers of the content object to the devices. Thecache controller may compare the available scalable layers to theproperty information (e.g., capability information) of the devices. Theresult of the comparison may be used to determine which scalable layersare relevant to which device, and/or whether an available scalable layerfor a program may be decoded by/used by a device to which the programitself has been determined relevant. The comparison may be conductedbased on the layer type and/or associated parameters of the availablescalable layer including, for example, an associated bit rate, framerate, resolution, an associated profile, and/or an associated level. Theproperty information (e.g., capability information) of the devices maybe received as described herein.

In the “Checkmate” example given herein, the cache controller maydetermine that the latest episode of the show is relevant to threedevices: a mobile phone, a tablet device, and a 4K UHD TV in a homenetwork. The cache controller may obtain scalable layer availability forthe latest episode of the show. The cache controller may determine thefollowing with respect to the scalable layers' availability. A firstscalable layer (e.g., a base layer representation) may allow decoding ofthe content at a standard definition resolution. A second scalable layer(e.g., a spatial scalable enhancement layer representation) whencombined with the base layer may allow decoding of the content at 1080 presolution. A third scalable layer (e.g., a combined spatial scalableand color gamut scalable enhancement layer) when combined with the firsttwo scalable layers may allow decoding of the content at 4K UHDresolution with an enhanced BT.2020 color gamut. Comparing the layerinformation to the property information (e.g., capability information)for the three devices for which the “Checkmate” episode is relevant, thecache controller may make the following determinations. All threedevices may be capable of using (e.g., decoding, playing, and/orpossibly caching) the first layer, and as such the first layer may berelevant to all three devices. Both the tablet device and the 4K UHD TVmay be capable of using the second layer, but the mobile phone lackssuch capability (e.g., the mobile phone may not be capable of displaying1080 p resolution, or it may not support a profile/level associated withthe second scalable layer, or it may not support scalable decoding).Therefore, the second layer may be relevant to the tablet device and the4K UHD TV, but not to the mobile phone. The 4K UHD TV may be capable ofusing the third layer (e.g., the 4K UHD TV may support the full 4K UHDresolution, decoding and display of the enhanced BT.2020 color gamut,and/or a coding/profile/level combination associated with the thirdlayer), while the tablet device may be incapable of using the thirdlayer. Thus, the third layer may be relevant only to the 4K UHD TV.

The cache controller may determine a mapping of the available scalablelayers to cache locations. The determination may be made based on one ormore factors including, for example, the following: the relevance of thescalable layers to the devices, the caching capabilities of the devices,available storage space on the devices (e.g., assuming the devices arecache-capable devices), the presence or absence of a home gateway,and/or the presence or absence of other caching devices (e.g., cachedevices that are accessible to multiple devices) to which a scalablelayer is relevant, such as a local media server in the home network.

In the “Checkmate” example given herein, the cache controller may havedetermined the following. The first scalable layer of the latest‘Checkmate’ episode may be relevant to the mobile phone, the tabletdevice, and the 4K UHD TV. The second scalable layer may be relevant tothe tablet device and the 4K UHD TV. The third scalable layer may berelevant to the 4K UHD TV. The cache controller may know (e.g., based onprocessing described herein) that there is a cache-capable home gatewayin the home network, and that all three devices may access content(e.g., scalable layer content) cached on the gateway. The cachecontroller may have obtained (e.g., from processing described herein)information on cache capabilities and/or information on current cachespace available for both the gateway and the three end user devices. Thecache controller may determine that the first and second layers (e.g.,which may be relevant to more than one device) should be cached on thehome gateway, and that the third layer (e.g., which may be relevant onlyto the 4K UHD TV) should be cached on the 4K UHD TV. The cachecontroller may verify that the home gateway has sufficient cache spaceto store the first and second scalable layers of the “Checkmate”episode, and that the 4K UHD TV has sufficient cache space to store thethird scalable layer. If sufficient cache space is lacking (e.g., on anyof the devices), the cache controller may take actions accordingly. Forexample, the cache controller may instruct the home gateway and/or the4K UHD TV to remove from their cache older content or content lesslikely to he used in order to make room for the scalable layer contentof the newly identified Checkmate episode. For example, the cachecontroller may determine an alternate cache configuration which meetsthe needs of the devices to which the Checkmate episode is relevant. Forexample, if the home gateway lacks sufficient cache space, the cachecontroller may determine an alternate caching structure where the firstlayer may be cached on the mobile phone, the first and second layers maybe cached on the tablet, and all three layers may be cached on the 4K⁻UHD TV.

The mapping of available scalable layers to cache locations may includeallowing one or more devices to retrieve (e.g., at play time) a scalablelayer from a location outside the home network. The outside location maybe a CDN cache, a content origin server, and/or the like. For instance,in the “Checkmate” example given herein, a possible mapping may be tocache the first layer on the mobile phone and the tablet device, tocache the first and third layers on the 4K UHD TV, and to not cache thesecond layer within the home network (e.g., to have the tablet deviceand/or the 4K UHD TV retrieve the second layer from a CDN cache or fromthe origin server at playback time).

When considering the viability of a caching structure (e.g., a mappingfrom scalable layers to cache locations), the cache controller mayexamine a plurality of factors. These factors may include, for example,the available network connection types, connection speeds of the variousdevices, whether a device is fixed or mobile, and/or how much time adevice spends in the home network. The potential impact of the factorson caching structure may be illustrated as follows.

If a device is mobile and frequently watches content when the device isoutside of the home network, the cache controller may make such a device“self-contained” in that it may have the base layer (e.g., the baselayer and one or more scalable enhancement layers) cached on the device.For example, if a mobile phone is often used to watch the ‘Checkmate’show outside the home network, then the cache controller may cache thebase layer on the mobile phone directly, rather than having the mobilephone retrieve the base layer from another cache device (e.g., from thehome gateway cache).

If a device is fixed or is used to watch the content typically withinthe home network, then the cache controller may cache enough scalablelayers on the device such that the remaining layers may be streamed atplayback time via a home network connection (e.g., at its typicalavailable speed, which may be estimated based on observed usage). Forexample, direct caching on a device may be used to reduce the bandwidthneeded at play time so that it is within the expected availablebandwidth (e.g., the bandwidth available in the home network at the timesuch content is expected to be watched).

If a device watches content both inside the home network and outside thehome network (e.g., over a cellular network), the cache controller mayarrange the caching operation to take both scenarios into consideration.For example, if the device is connected over a cellular network, cachingmay be arranged such that at playback time the layers not cacheddirectly on the device may be retrieved using the expected cellularconnection speed. If the playback is from within the homework, cachingmay be arranged such that the layers not cached directly on the deviceand not available from the home gateway or other cache within the homenetwork may be retrievable using the expected home network connectionspeed.

Redundancy may be included in the connection speed calculation. Takingredundancy into consideration may account for other possible networkusage in addition to usage by the streaming device. For example, in thehome network it is possible that multiple devices may stream contentsimultaneously. The cache controller may take such usage intoconsideration when determining the connection speed (e.g., from thepoint of view of a cache device), Network connection types and/orobserved speed data may be provided to the cache controller (e.g., aspart of the processing that obtains device characteristics). The layersnot available from cache within the home gateway may, in some cases, beavailable from the outside cache or origin server in multiple bitrates(e.g., in an Adaptive Bitrate format such as MPEG DASH). The predictionof available connection speed may be skipped (e.g., in the scenariosdescribed above).

The cache controller may direct various devices to cache the scalablelayers that are determined to be mapped to each device. For example, thecache controller may send a message to a caching device (e.g., the homegateway, another caching device, a cache-capable end user device, etc.)to instruct the cache device to store a particular set of scalablelayers for one or more content objects. The message may identify thecontent objects and the scalable layers of such objects that the cachedevice should store. The message may identify the locations (e.g., usingURLs or other identifiers) from which the scalable layers may beretrieved and/or the time such retrieval may be carried out. Inresponse, the cache device may request, retrieve, and cache the scalablelayers based on the instructions sent by the cache controller.

The cache controller described herein may be located in various places.For example, the cache controller may be located in a general publicnetwork such as the Internet, a content delivery network such as a CDNnetwork, or a mobile network), a corporate network (e.g., within theback-end infrastructure of a content provider or content distributor), ahome network a home gateway, a router, or in an end user device), and/orthe like.

FIG. 10 shows an example of cache control using a network-basedcontroller (e.g., the controller may reside outside a home network).Such a cache controller may be referred to herein as a network-basedcache controller. The network in which the cache controller resides mayinclude, for example, the Internet, a CDN network, a content providernetwork, a content distributor network, and/or the like. Thenetwork-based cache controller may control caching for one contentprovider or for multiple content providers. The network-based cachecontroller may control caching for multiple end user devices, as shownin the figure.

The network-based cache controller may be configured to execute one ormore of the functions described herein (not all are shown in FIG. 10).For example, the cache controller may obtain a list of devices that mayinclude, for example, a mobile phone, a tablet device, and/or a TVdevice. The list may be obtained, e.g., by installing an application orsuitable software on the devices, as described herein. The applicationor software may communicate to the cache controller and identify thedevices. The cache controller may obtain property information (e.g.,capability information) of the devices and/or user content preferenceassociated with the devices. The devices may report the contentpreference to the cache controller. Alternately or additionally, acontent service may report the content preference of the devices to thecache controller. The cache controller may perform other functionsincluding, for example, obtaining program availability, determiningwhich programs are relevant to which devices, obtaining scalable layeravailability (e.g., for the programs or content objects which arerelevant to at least one of the devices), determining which scalablelayers of the programs are relevant to which devices, and/or determininga mapping of such scalable layers to the devices with cachingcapabilities.

Based on the mapping of scalable layers to devices, the cache controllermay send caching requests to one or more of the devices. The requestsmay instruct the devices to cache the scalable layers which the mappingindicates should be cached by the respective devices. In response to thecaching instruction, the devices may request and cache the relevantscalable layers from an available location (e.g., from a content originserver or a CDN cache, which may be identified in the cachinginstruction).

When playing back media content, a device (e.g., the phone, tablet, orTV shown in FIG. 10) may use any or all of the scalable layers stored inthe device's local cache. For example, after a device executes thecaching instructions as shown FIG. 10, the device may perform one ormore of the following actions. The device may have all the layers itneeds for a program stored in advance in its local cache, in which caseat playback time the device may play the content for that programentirely from its local cache. The device may have a subset of thelayers it needs for a program stored in advance in its local cache, inwhich case at playback time the device may utilize the layers availablefrom its local cache together with one or more layers streamed fromanother cache location (e.g., from an origin server or from a cacheoutside the device). The device may not have any layers cached for agiven program. For example, the cache controller may not have been ableto predict the program that would be relevant to the device, in whichcase the cache controller may not have instructed the device to cacheany layers for the program. In such a situation, the device may streamthe content (e.g., the entire content) from an outside source such as anorigin server or a CDN cache at playback time.

FIG. 11 shows another example of a cache controller residing outside ofa home network and interacting with a home gateway. The home gateway mayhave caching capabilities. The cache controller may be referred toherein as a network-based cache controller with home gateway cache. Thecache controller itself may reside on the Internet, a CDN network, acontent provider network, a content distributor network, and/or anothersuitable type of networks. The cache controller may control the cachingof content for one content provider or for multiple content providers.The cache controller may control the caching of content on the homegateway and/or other end user devices, as shown in FIG. 11.

The network-based cache controller with home gateway cache may beconfigured to execute one or more of the functions described herein (notall are shown in FIG. 11). For example, the cache controller may obtaininformation about a list of devices including, for example, the homegateway, a tablet device, and/or a 4K MD TV. The list of devices may beconnected to a home network. As such, information about the devices maybe obtained via a device discovery protocol (e.g., such as UNP) runningon the home gateway. The home gateway may constrict the list and/orcommunicate the list to the cache controller. The list may include thehome gateway as a cache-capable device, and/or the discovered end userdevices. The cache controller may obtain property information (e.g.,capability information) for the devices (including the home gateway).For example, the devices may directly communicate their propertyinformation (e.g., capability information) to the cache controller, orthe home gateway may obtain the property information (e.g., capabilityinformation) from the devices and communicate such information to thecache controller. The property information (e.g., capabilityinformation) may describe the capability of the home gateway and/or thecapability of the end-user devices. The property information (e.g.,capability information) may be included in the same communication thatidentifies the list of devices.

The network-based cache controller with home gateway cache may obtainuser content preference (e.g., which may be reflected through or derivedfrom the user's viewing habits, viewing history, and/or servicesubscription) associated with an end device. For example. as shown inFIG. 11, an end user device may report viewinghistory/habits/preferences to the cache controller. Alternately oradditionally, a content service may report the viewinghistory/habits/preferences for an end user device to the cachecontroller. The cache controller may execute one or more other functionsincluding, for example, obtaining program availability, determiningwhich programs are relevant to which devices, obtaining scalable layeravailability (e.g., for the programs or content objects which arerelevant to at least one of the devices), determining which scalablelayers of the programs are relevant to which devices, and/or determininga mapping of such scalable layers to the devices with cachingcapabilities.

Based on the mapping of scalable layers to devices, the cache controllermay send caching requests to one or more of the devices. The requestsmay instruct the devices to cache the scalable layers which the mappingindicates should be cached by the respective devices. In response to thecaching instruction, the devices may request and cache the relevantscalable layers from an available location (e.g., from a content originserver or a CDN cache, which may be identified in the cachinginstruction). For example, scalable layers that may be useful to orusable by both the tablet device and the 4K UHD TV may be cached in thehome gateway cache, while scalable layers that may be useful to orusable by only one of the two end user devices may be cached directly onthe end-user device for which the layer is relevant.

When playing back media content, an end user device may determine whichscalable layers are needed. The end user device may access such layersfrom one or more sources including, e.g., from its local cache, from thecache in the home gateway, and/or from an outside source such as a CDNcache or a content origin server.

FIG. 12 shows an example of a cache controller residing within a homegateway (e.g., the home gateway may have caching capabilities). Such acache controller may be referred to herein as a gateway-based cachecontroller and may be implemented in different ways. For example, thecache controller may be built into the home gateway. The cachecontroller may be implemented as software installed and running on thehome gateway. Further, although FIG. 12 may indicate that the cachecontroller physically resides in a home gateway, one skilled in the artwill recognize that the example may be applicable to scenarios in whichthe cache controller resides within a different entity of the homenetwork. For example, the cache controller may be software running on aPC, or the cache controller may be built into a home media serverdevice, or the cache controller may reside in a router that is separatefrom the home gateway. More generally, the cache controller may residein any device within the home network that is capably, of communicatingwith various other end user devices in the home network, and/or that maycommunicate with remote content providers/content servers. The cachecontroller may control the caching of content for one content provideror for multiple content providers. The cache controller may control thecaching of content on the home gateway and/or other end user devices.

The gateway-based cache controller may be configured to execute one ormore of the functions described herein (not all are shown in FIG. 12).For example, the cache controller may obtain a list of devices which mayinclude the home gateway, an HDTV, a 4K UHD TV, and/or a tablet device.The list of devices may be obtained via a device discovery protocol(e.g., such as UPnP) running on the home gateway or another device inthe home network (e.g., a UPnP program may discover the devices andconstruct the list). The list may be passed to the gateway-based cachecontroller. The list may include the home gateway as a cache-capabledevice and/or the discovered end user devices. The cache controller mayobtain property information (e.g., capability information) for thedevices. For example, the devices may directly communicate theirproperty information (e.g., capability information) to the cachecontroller, or the home gateway or another device in the home networkmay obtain the property information (e.g., capability information) fromthe devices and communicate such information to the cache controller.The property information (e.g., capability information) may describe thecapability of the home gateway and/or the discovered end-user devices.The property information capability information) may be included in thesame communication that identifies the list of devices.

The gateway-based cache controller may obtain user content preference(e.g., which may be reflected through or derived from the user's viewinghabits, viewing history, and/or service subscription) associated with anend user device. For example, as shown in FIG. 12, an end user devicemay report the viewing preferences/habits/history to the gateway-basedcache controller. Alternately or additionally, a content services mayreport the viewing preferences/habits/history for an end user device tothe gateway-based cache controller. The gateway-based cache controllermay execute one or more other functions, including, for example,obtaining program availability, determining which programs are relevantto which devices, obtaining scalable layer availability (e.g., for theprograms or content objects which are relevant to at least one of thedevices), determining which scalable layers of the programs are relevantto which devices, and/or determining a mapping of such scalable layersto the devices with caching capabilities. These and other examplefunctions may be represented in the aggregate as “learning” by the cachecontroller.

Based on the mapping of scalable layers to devices, the cache controllermay instruct the home gateway to request the media content determined tobe relevant. The media content may be stored in the local cache of thehome gateway. The cache controller may send caching requests to one ormore other devices identified by the mapping. The requests may instructthe devices to cache the scalable layers which the mapping indicatesshould be cached by the respective devices. In response to the cachinginstruction, the devices may request and cache the relevant scalablelayers from an available location (e.g., from a content origin server ora CDN cache, which may be identified in the caching instruction). Forexample, scalable layers that may be useful to or usable by both thetablet device and the 4K UHD TV may be cached in the home gateway cache,while scalable layers that may be useful to or usable by only one of thetwo end user devices may be cached directly on the end-user device forwhich the layer is relevant

When playing back media content, an end user device may determine whichscalable layers arc needed. The end user device may access such layersfrom one or more sources, e.g., from its local cache, from the cache inthe home gateway, and/or from an outside source such as a CDN cache ororigin server.

FIG. 13 shows an example of a cache controller residing within anend-user device. Such a cache controller may be referred to herein as adevice-based cache controller. The device-based cache controller mayreside in a phone device, in a tablet, in a TV device, in a set-top box,or in various other end user devices (e.g., other WTRUs as describedherein) that may have the capability to cache and/or play back mediacontent. The device-based cache controller may control local caching ofmedia content. The media content may be from one content provider orfrom multiple content providers. The device-based cache controller maybe implemented in various ways, as illustrated by the followingexamples. The cache controller may be implemented as software running onthe end user device. The cache controller may be part of a mediaplayback client (e.g., a general playback client or a client specific toa content service). The cache controller may be part of a DASH client.The cache controller may be provided as pre-installed software. Thecache controller may be part of the operating system of the end userdevice.

The device-based cache controller may be configured to execute one ormore of the functions described herein (not all are shown in FIG. 13).For example, the device-based cache controller may have or may obtainproperty information (e.g., capability information) for the device onwhich the cache controller resides. Such information may be built intothe software (e.g., a media playback client) of which the cachecontroller may be a part. The information may be accessible via an APIto the software or to the device OS. The device-based cache controllermay track or may obtain user viewing preferences/history/habits for thedevice on which the cache controller resides. In an example, the cachecontroller may be implemented within a media playback client (e.g., aclient specific to a content service) and the user viewingpreferences/history/habits may be available within the media client. Inan example, the user viewing preferences/history/habits may be requestedfrom the one or more content providers for which the cache controllercontrols caching. The viewing preferences/history/habits of the end userdevice may be tracked in an ongoing manner (e.g., by a playback clientor by a content provider) as the user selects content to watch on theend user device.

The device-based cache controller may execute one or more otherfunctions, including, for example, obtaining program availability,determining which programs are relevant to the device on which the cachecontroller resides, obtaining scalable layer availability (e.g., for theprograms or content objects which are relevant to the device),determining which scalable layers of the programs are relevant to thedevice, and/or determining which scalable layers should be stored in alocal cache of the device. These and other example functions may berepresented in the aggregate as “learning” by the cache controller.

The device-based cache controller may instruct the device on which itresides to request the scalable layers of media content determined to berelevant to the device. The scalable layers may be received and/orstored in advance of playback. The scalable layers may be stored withinlocal cache space on the device. The cache controller may manage thelocal cache space. The requesting, receiving and storing operationsdescribed herein may be repeated periodically. The cache controller maydecide which layers of which content objects (e.g., the content objectmay be a TV program) should be kept in the local cache at a given time.In some situations (e.g., when programs are determined to be no longerrelevant or less important than newly available programs), the cachecontroller may remove previously cached scalable layers of a programfrom the local cache and may instruct the device to retrieve relevantscalable layers of a newly available program into the local cache. Theremay be multiple device-based cache controllers (e.g., a cache controllerrunning on each individual device of a home network), in which scenariothe operations described herein may be executed independently by thecache controllers.

When playing back media content, the device may utilize any scalablelayers that have been cached into the device's local device cache. Otheravailable scalable layers from outside sources (e.g., from originservers and/or CDN cache locations) may be streamed as needed, e.g.,based on a number of criteria, as described herein.

A DASH MPD may support multiple and/or alternative segment locations(e.g., by using a BaseURL tag or element). The support may be providedsuch that identical segments may be accessible at multiple locations.For example, a DASH streaming device (e.g., a DASH client) may use thebase URLs provided in the BaseURL tag/element. The DASH streaming devicemay determine which URLs to use for a request.

For SHVC, an enhancement layer may depend on one or more lower layersfor decoding. Different segments from different sources may besynchronized. Layer based buffer management may be deployed at clientside (e.g., on a streaming device), for example, with a leaky bucketmodel, to balance buffer levels (e.g., buffer fullness) for thestreaming sources. The streaming device may allocate individual buffersfor the respective streaming sources. Inter-dependencies among thestreaming sources may be considered for buffer control.

FIG. 14 shows an example of video streaming from multiple sources.Streaming devices C and D may receive streams from two content sources Aand B (e.g., the content sources may include edge server A0, A1, and/ora content server B) simultaneously. The streams from source B may beenhancement layer representations of media content, which may depend onthe streams from source A (e.g., base layer representations of the mediacontent). The arrival times of the streams (e.g., which may correspondto segments from different layers) may be different. The streamingdevices may synchronize the streams (e.g., the segments) based on theirrespective arrival times.

FIGS. 15A and 15B show example buffer models for a multi-sourcestreaming scenario. As shown in the examples, the segments in Buffer-0and Buffer-1 may be synchronized based on the segments' respectivearrival times (T_(i)) at a streaming device. In the example shown inFIG. 15A, the arrival time T_(1,3) of segment S3 (e.g., an enhancementlayer segment from server B) in Buffer-1 may be ahead of the arrivaltime T_(0,3) of its dependent layer segment (e.g., a base layer segmentfrom server A) in Buffer-0. In this scenario, the streaming device maydecide to stop fetching segments from server B. More generally, assuminga (i+1)-th layer depends on an i-th layer, the downloading of a j-thsegment of the (i+1)-th layer may be terminated when the j-th segment ofthe (i+1)-th layer arrives ahead of the j-th segment of the i-th layerby a threshold amount. Such a condition may be represented by (2) below.

T _(i,j) +T _(i+1,j)>Threshold   (2)

The value of Threshold in (2) may be determined based on the timedifference between the current playback time and the playback time ofthe j-th segment of the video. For example, if the current segment is at5 min:00 sec of the video, and the playback time of the j-th segment is6 min:30 sec, then the value of Threshold may be set to a value below(e.g., slightly below) 1 min:30 sec. Such a threshold value may allowthe (i+1)-th layer to arrive in time for decoding and playback. Thethreshold value may be pre-defined, set dynamically, and/or determinedin various other suitable ways

Media content may be coded into multiple layers (e.g., an EL layer and aBL layer). In some cases, a streaming device may receive streams for themultiple layers from a shared link (e.g., such as streaming device Dshown in FIG. 14). In some cases, a streaming device may receive thestreams for the multiple layers with separate links (e.g., such asstreaming device C shown in FIG. 14). In the former scenario, morebandwidth may be allocated to download the base layer stream.

in the example shown in FIG. 15B, the arrival time To of an enhancementlayer S3 in Buffer-1 may be behind the arrival time To, of the segment'sdependent layer segment in Buffer-0 buffer. The streaming device in sucha scenario may request that lower bitrate segments be transmitted fromthe slower source (e.g., from server B). This way, segments from theslower source (e.g., the EL segments in Buffer-1) may be aligned withthe segments from the faster source (e.g., the BL segments in Buffer-0,which are downloaded from server A).

The request for lower bitrate representation of a j-th segment of themedia content may be expressed as (3). As shown, such a request may bemade when the arrival time T_(i+1,j) of the j-th segment of the (i+1)-thlayer is behind the arrive time T_(i,j) of the j-th segment of the i-thmay by a threshold value. The threshold value may be pre-defined, setdynamically, and/or determined in various other suitable ways.

T_(i+1,j) −T _(i,j)>Threshold   (3)

A client may request different layer segments from different sources(e.g., as shown in FIG. 14). The size of a base layer segment may besmaller than the size of an enhancement layer segment. The link betweenthe client and the server/cache storing the base layer content may befaster than the link between the client and the server storing theenhancement layer content. When necessary, the client may switch tolower bitrate segments of the enhancement layer to maintain the qualityof playback. A DASH streaming device (e.g., a DASH client) may streammultiple segments in parallel. The bandwidth of multiple downlink pathsmay be utilized. FIG. 16A shows an example scheme for a DASH streamingdevice (e.g., a DASH client) to request different layer segments fromdifferent locations. FIG. 16B shows an example scheme for a DASHstreaming device to request different segments of the same layer fromdifferent locations.

When requesting different layer segments from different locations (e.g.,each location may correspond to a link such as a URL), the segmentarrival time gap may be reduced (e.g., as shown in FIGS. 16A-16B). Astreaming device may select a link for a particular layer segment basedon the respective sizes of the layer segments and/or the availablebandwidths of the links. Base layer segments may be fetched prior toenhancement layer segments, for example, based on the relationship shownin (4).

$\begin{matrix}{\frac{S_{i,j}}{{BW}_{k}} \geq \frac{S_{0,j}}{{BW}_{n}}} & (4)\end{matrix}$

S_(i,j) may represent the size of the j-th segment of the i-th layer.S_(o,j) may represent the size of the j-th segment of the base layer.BWk, BWn may represent the bandwidths of the k-th and n-th links,respectively. As shown in (4), the k-th and n-th links may be selectedbased on the respective segment sizes and available bandwidths so thatthe base layer representation may be downloaded via the n-th link beforethe enhancement layer representation may be download via the k-th link.More generally, a streaming device may choose a different link torequest a different segment, e.g., based on the estimated bandwidths ofthe links and the sizes of the segments.

Although in the below examples wireless network details are provided,the embodiments described herein may be implemented and/or used, forexample, in a wired and/or wireless network (e.g., in device(s) of suchnetworks, such as network devices, end user devices, etc.). Thesedevices may include a wireless transmit/receive unit (WTRU) that workswirelessly or a WTRU used in a wired network (e.g., a computer or otherend user device with a wired connection to the network). These devicesmay include home network devices (e.g., TVs, set-top boxes, gateways,routers) that may work wirelessly or in a wired network. Forillustration purposes, the disclosure below describes an examplewireless communication network 500 (e.g., as shown in FIG. 17A) in whichone or more disclosed embodiments may be implemented or used.

The communications system 500 may be a multiple access system thatprovides content, such as voice, data, video, messaging, broadcast,etc., to multiple wireless users. The communications system 500 mayenable multiple wireless users to access such content through thesharing of system resources, including wireless bandwidth. For example,the communications systems 500 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA. (OFDMA), single-carrier FDMA (SC-FDMA), and the like.

As shown in FIG. 17A, the communications system 500 may include wirelesstransmit/receive units (WTRUs) 502 a, 502 b, 502 c, and/or 502 d (whichgenerally or collectively may be referred to as WTRU 502), a radioaccess network (RAN) 503/504/505, a core network 506/507/509, a publicswitched telephone network (PSTN) 508, the Internet 510, and othernetworks 512, though it will be appreciated that the disclosedembodiments contemplate any number of WTRUs, base stations, networks,and/or network elements. Each of the WTRUs 502 a, 502 b, 502 c, and/or502 d may be any type of device configured to operate and/or communicatein a wireless environment. By way of example, the WTRUs 502 a, 502 b,502 c, and/or 502 d may be configured to transmit and/or receivewireless signals and may include user equipment (UE), a mobile station,a fixed or mobile subscriber unit, a pager, a cellular telephone, apersonal digital assistant (PDA), a smartphone, a laptop, a netbook, apersonal computer, a wireless sensor, consumer electronics, and thelike.

The communications systems 500 may also include a base station 514 a anda base station 514 b. Each of the base stations 514 a, 514 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 502 a, 502 b, 502 c, and/or 502 d to facilitate access to oneor more communication networks, such as the core network 506/507/509,the Internet 510, and/or the networks 512. By way of example, the basestations 514 a and/or 514 b may be a base transceiver station (BTS), aNode-B, an eNode B, a Home Node B, a Home eNode B, a site controller, anaccess point (AP), a wireless router, and the like. While the basestations 514 a, 514 b are each depicted as a single element, it will beappreciated that the base stations 514 a, 514 b may include any numberof interconnected base stations and/or network elements.

The base station 514 a may be part of the RAN 503/504/505, which mayalso include other base stations and/or network elements (not shown),such as a base station controller (BSC), a radio network controller(RNC), relay nodes, etc. The base station 514 a and/or the base station514 b may be configured to transmit and/or receive wireless signalswithin a particular geographic region, which may be referred to as acell (not shown). The cell may further be divided into cell sectors. Forexample, the cell associated with the base station 514 a may be dividedinto three sectors. Thus, in one embodiment, the base station 514 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 514 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 514 a and/or 514 b may communicate with one or more ofthe WTRUs 502 a, 502 b, 502 c, and/or 502 d over an air interface515/516/517, which may be any suitable wireless communication link(e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV),visible light, etc.). The air interface 515/516/517 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 500 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA., and the like. Forexample, the base station 514 a in the RAN 503/504/505 and the WTRUs 502a, 502 b, and/or 502 c may implement a radio technology such asUniversal Mobile Telecommunications System (UMTS) Terrestrial RadioAccess (UTRA), which may establish the air interface 515/516/517 usingwideband CDMA (WCDMA). WCDMA may include communication protocols such asHigh-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA mayinclude High-Speed Downlink Packet Access (HSDPA) and/or High-SpeedUplink Packet Access (HSUPA).

In another embodiment, the base station 514 a and the WTRUs 502 a, 502b, and/or 502 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface515/516/517 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

in other embodiments, the base station 514 a and the WTRUs 502 a, 502 b,and/or 502 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), interimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 514 b in FIG. 17A may be a wireless router, Home NodeB, Home eNode B, or access point, for example, and may utilize anysuitable RAT for facilitating wireless connectivity in a localized area,such as a place of business, a home, a vehicle, a campus, and the like.In one embodiment, the base station 514 b and the WTRUs 502 c, 502 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 514 band the WTRUs 502 c, 502 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 514 b and the WTRUs 502 c, 502 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 17A,the base station 514 b may have a direct connection to the Internet 510.Thus, the base station 514 b may not he required to access the Internet510 via the core network 506/507/509.

The RAN 503/504/505 may be in communication with the core network506/507/509, which may be any type of network configured to providevoice, data, applications, and/or voice over internet protocol (VoIP)services to one or more of the WTRUs 502 a, 502 b, 502 c, and/or 502 d.For example, the core network 506/507/509 may provide call control,billing services, mobile location-based services, pre-paid calling,Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 17A, it will be appreciated that the RAN 503/504/505and/or the core network 506/507/509 may be in direct or indirectcommunication with other RANs that employ the same RAT as the RAN503/504/505 or a different RAT. For example, in addition to beingconnected to the RAN 503/504/505, which may be utilizing an E-UTRA radiotechnology, the core network 506/507/509 may also be in communicationwith another RAN (not shown) employing; a GSM radio technology.

The core network 506/507/509 may also serve as a gateway for the WTRUs502 a, 502 b, 502 c, and/or 502 d to access the PSTN 508, the Internet510, and/or other networks 512. The PSTN 508 may includecircuit-switched telephone networks that provide plain old telephoneservice (POTS). The Internet 510 may include a global system ofinterconnected computer networks and devices that use commoncommunication protocols, such as the transmission control protocol(TCP), user datagram protocol (UDP) and the internet protocol (IP) inthe TCP/IP internet protocol suite. The networks 512 may include wiredor wireless communications networks owned and/or operated by otherservice providers. For example, the networks 512 may include anothercore network connected to one or more RANs, which may employ the sameRAT as the RAN 503/504/505 or a different RAT.

Some or all of the WTRUs 502 a, 502 b, 502 c, and/or 502 d in thecommunications system 500 may include multi-mode capabilities, i.e., theWTRUs 502 a, 502 b, 502 c, and/or 502 d may include multipletransceivers for communicating with different wireless networks overdifferent wireless links. For example, the WTRU 502 c shown in FIG. 17Amay be configured to communicate with the base station 514 a, which mayemploy a cellular-based radio technology, and with the base station 514b, which may employ an IEEE 802 radio technology.

FIG. 17B depicts a system diagram of an example WTRU 502. As shown inFIG. 17B, the WTRU 502 may include a processor 518, a transceiver 520, atransmit/receive element 522, a speaker/microphone 524, a keypad 526, adisplay/touchpad 528, non-removable memory 530, removable memory 532, apower source 534, a global positioning system (GPS) chipset 536, andother peripherals 138. It will be appreciated that the WTRU 502 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment. Also, embodiments contemplate that thebase stations 514 a and 514 b, and/or the nodes that base stations 514 aand 514 b may represent, such as but not limited to transceiver station(BTS), Node-B, a site controller, an access point (AP), a home node-B,an evolved home node-B (eNodeB), a home evolved node-B (HeNB), a homeevolved node-B gateway, and proxy nodes, among others, may include someor all of the elements depicted in FIG. 17B and described herein.

The processor 518 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 518 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 502 to operate in a wirelessenvironment. The processor 518 may be coupled to the transceiver 520,which may be coupled to the transmit/receive element 522. While FIG. 17Bdepicts the processor 518 and the transceiver 520 as separatecomponents, it may be appreciated that the processor 518 and thetransceiver 520 may be integrated together in an electronic package orchip.

The transmit/receive element 522 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 514a) over the air interface 515/516/517. For example, in one embodiment,the transmit/receive element 522 may be an antenna configured totransmit and/or receive RF signals. In another embodiment, thetransmit/receive element 522 may be an emitter/detector configured totransmit and/or receive IR, UV, or visible light signals, for example.In yet another embodiment, the transmit/receive element 522 may beconfigured to transmit and receive both RF and light signals. It will beappreciated that the transmit/receive element 522 may be configured totransmit and/or receive any combination of wireless signals.

In addition, although the transmit/receive element 522 is depicted inFIG. 17B as a single element, the WTRU 502 may include any number oftransmit/receive elements 522. More specifically, the WTRU 502 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 502 mayinclude two or more transmit/receive elements 522 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 515/516/517.

The transceiver 520 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 522 and to demodulatethe signals that are received by the transmit/receive element 522. Asnoted above, the WTRU 502 may have multi-mode capabilities. Thus, thetransceiver 520 may include multiple transceivers for enabling the WTRU502 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 518 of the WTRU 502 may be coupled to, and may receiveuser input data from, the speaker/microphone 524, the keypad 526, and/orthe display/touchpad 528 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor518 may also output user data to the speaker/microphone 524, the keypad526, and/or the display/touchpad 528. In addition, the processor 518 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 530 and/or the removable memory 532.The non-removable memory 530 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 532 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 518 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 502, such as on a server or a home computer (notshown).

The processor 518 may receive power from the power source 534, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 502. The power source 534 may be any suitabledevice for powering the WTRU 502. For example, the power source 534 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 518 may also be coupled to the GPS chipset 536, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 502. In additionto, or in lieu of, the information from the GPS chipset 536, the WTRU502 may receive location information over the air interface 515/516/517from a base station (e.g., base stations 514 a, 514 b) and/or determineits location based on the timing of the signals being received from twoor more nearby base stations. It will be appreciated that the WTRU 502may acquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 518 may further he coupled to other peripherals 538, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an c-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 17C depicts a system diagram of the RAN 503 and the core network506 according to an embodiment. As noted above, the RAN 503 may employ aUTRA radio technology to communicate with the WTRUs 502 a, 502 b, and/or502 c over the air interface 515. The RAN 503 may also be incommunication with the core network 506. As shown in FIG. 17C, the RAN503 may include Node-Bs 540 a, 540 b, and/or 540 c, which may eachinclude one or more transceivers for communicating with the WTRUs 502 a,502 b, and/or 502 c over the air interface 515. The Node-Bs 540 a, 540b, and/or 540 c may each be associated with a particular cell (notshown) within the RAN 503. The RAN 503 may also include RNCs 542 aand/or 542 b. It will be appreciated that the RAN 503 may include anynumber of Node-Bs and RNCs while remaining consistent with anembodiment.

As shown in FIG. 17C, the Node-Bs 540 a and/or 540 b may be incommunication with the RNC 542 a. Additionally, the Node-B 540 c may bein communication with the RNC542 b. The Node-Bs 540 a, 540 b, and/or 540c may communicate with the respective RNCs 542 a, 542 b via an Tubinterface. The RNCs 542 a, 542 b may be in communication with oneanother via an Iur interface. Each of the RNCs 542 a, 542 b may beconfigured to control the respective Node-Bs 540 a, 540 b, and/or 540 cto which it is connected. In addition, each of the RNCs 542 a, 542 b maybe configured to carry out or support other functionality, such as outerloop power control, load control, admission control, packet scheduling,handover control, macrodiversity, security functions, data encryption,and the like.

The core network 506 shown in FIG. 17C may include a media gateway (MGW)544, a mobile switching center (MSC) 546, a serving GPRS support node(SGSN) 548, and/or a gateway GPRS support node (GGSN) 550. While each ofthe foregoing elements are depicted as part of the core network 506, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 542 a in the RAN 503 may be connected to the MSC 546 in the corenetwork 506 via an IuCS interface. The MSC 546 may be connected to theMGW 544. The MSC 546 and the MGW 544 may provide the WTRUs 502 a, 502 b,and/or 502 c with access to circuit-switched networks, such as the PSTN508, to facilitate communications between the WTRUs 502 a, 502 b, and/or502 c and traditional land-line communications devices.

The RNC 542 a in the RAN 503 may also be connected to the SGSN 548 inthe core network 506 via an IuPS interface. The SGSN 548 may beconnected to the GGSN 550. The SGSN 548 and the GGSN 550 may provide theWTRUs 502 a, 502 b, and/or 502 c with access to packet-switchednetworks, such as the Internet 510, to facilitate communications betweenand the WTRUs 502 a, 502 b, and/or 502 c and IP-enabled devices.

As noted above, the core network 506 may also be connected to thenetworks 512, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 17D depicts a system diagram of the RAN 504 and the core network507 according to an embodiment. As noted above, the RAN 504 may employan E-UTRA radio technology to communicate with the WTRUs 502 a, 502 b,and/or 502 c over the air interface 516. The RAN 504 may also be incommunication with the core network 507.

The RAN 504 may include eNode-Bs 560 a, 560 b, and/or 560 c, though itwill be appreciated that the RAN 504 may include any number of eNode-Bswhile remaining consistent with an embodiment. The eNode-Bs 560 a, 560b, and/or 560 c may each include one or more transceivers forcommunicating with the WTRUs 502 a, 502 b, and/or 502 c over the airinterface 516. In one embodiment, the eNode-Bs 560 a, 560 b, and/or 560c may implement MIMO technology. Thus, the eNode-B 560 a, for example,may use multiple antennas to transmit wireless signals to, and receivewireless signals from, the WTRU 502 a.

Each of the eNode-Bs 560 a, 560 b, and/or 560 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 17D, theNode-Bs 560 a, 560 b, and/or 560 c may communicate with one another overan X2 interface.

The core network 507 shown in FIG. 17D may include a mobility managementgateway (MME) 562, a serving gateway 564, and a packet data network(PDN) gateway 566.

While each of the foregoing elements are depicted as part of the corenetwork 507, it will be appreciated that any one of these elements maybe owned and/or operated by an entity other than the core networkoperator.

The MME 562 may be connected to each of the eNode-Bs 560 a, 560 b,and/or 560 c in the RAN 504 via an S1 interface and may serve as acontrol node. For example, the MME 562 may be responsible forauthenticating users of the WTRUs 502 a, 502 b, and/or 502 c, beareractivation/deactivation, selecting a particular serving gateway duringan initial attach of the WTRUs 502 a, 502 b, and/or 502 c, and the like.The MME 562 may also provide a control plane function for switchingbetween the RAN 504 and other RANs (not shown) that employ other radiotechnologies, such as GSM or WCDMA.

The serving gateway 564 may be connected to each of the eNode-Bs 560 a,560 b, and/or 560 c in the RAN 504 via the SI interface. The servinggateway 564 may generally route and forward user data packets to/fromthe WTRUs 502 a, 502 b, and/or 502 c. The serving gateway 564 may alsoperform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when downlink data isavailable for the WTRUs 502 a, 502 b, and/or 502 c, managing and storingcontexts of the WTRUs 502 a, 502 b, and/or 502 c, and the like.

The serving gateway 564 may also be connected to the PDN gateway 566,which may provide the WTRUs 502 a, 502 b, and/or 502 c with access topacket-switched networks, such as the Internet 510, to facilitatecommunications between the WTRUs 502 a, 502 b, and/or 502 c andIP-enabled devices.

The core network 507 may facilitate communications with other networks.For example, the core network 507 may provide the WTRUs 502 a, 502 b,and/or 502 c with access to circuit-switched networks, such as the PSTN508, to facilitate communications between the WTRUs 502 a, 502 b, and/or502 c and traditional land-line communications devices. For example, thecore network 507 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the core network 507 and the PSTN 508. In addition,the core network 507 may provide the WTRUs 502 a, 502 b, and/or 502 cwith access to the networks 512, which may include other wired orwireless networks that are owned and/or operated by other serviceproviders.

FIG. 17E depicts a system diagram of the RAN 505 and the core network509 according to an embodiment. The RAN 505 may be an access servicenetwork (ASN) that employs IEEE 802.16 radio technology to communicatewith the WTRUs 502 a, 502 b, and/or 502 c over the air interface 517. Aswill be further discussed below, the communication links between thedifferent functional entities of the WTRUs 502 a, 502 b, and/or 502 c,the RAN 505, and the core network 509 may be defined as referencepoints.

As shown in FIG. 17E, the RAN 505 may include base stations 580 a, 580b, and/or 580 c, and an ASN gateway 582, though it will be appreciatedthat the RAN 505 may include any number of base stations and ASNgateways while remaining consistent with an embodiment. The basestations 580 a, 580 b, and/or 580 c may each be associated with aparticular cell (not shown) in the RAN 505 and may each include one ormore transceivers for communicating with the WTRUs 502 a, 502 b, and/or502 c over the air interface 517. In one embodiment, the base stations580 a, 580 b, and/or 580 c may implement MIMO technology. Thus, the basestation 580 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 502 a.The base stations 580 a, 580 b, and/or 580 c may also provide mobilitymanagement functions, such as handoff triggering, tunnel establishment,radio resource management, traffic classification, quality of service(QoS) policy enforcement, and the like. The ASN gateway 582 may serve asa traffic aggregation point and may be responsible for paging, cachingof subscriber profiles, routing to the core network 509, and the like.

The air interface 517 between the WTRUs 502 a, 502 b, and/or 502 c andthe RAN 505 may be defined as an R1 reference point that implements theIEEE 802.16 specification. In addition, each of the WTRUs 502 a, 502 b,and/or 502 c may establish a logical interface(not shown) with the corenetwork 509. The logical interface between the WTRUs 502 a, 502 b,and/or 502 c and the core network 509 may be defined as an R2 referencepoint, which may be used for authentication, authorization, IP hostconfiguration management, and/or mobility management.

The communication link between each of the base stations 580 a, 580 b,and/or 580 c may be defined as an R8 reference point that includesprotocols for facilitating WTRU handovers and the transfer of databetween base stations. The communication link between the base stations580 a, 580 b, and/or 580 c and the ASN gateway 582 may be defined as anR6 reference point. The R6 reference point may include protocols forfacilitating mobility management based on mobility events associatedwith each of the WTRUs 502 a, 502 b, and/or 502 c.

As shown in FIG. 17E, the RAN 505 may be connected to the core network509. The communication link between the RAN 505 and the core network 509may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 509 may include a mobile IP home agent(MIP-HA) 584, an authentication, authorization, accounting (AAA) server586, and a gateway 588. While each of the foregoing elements aredepicted as part of the core network 509, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA may be responsible for IP address management, and may enablethe WTRUs 502 a, 502 b, and/or 502 c to roam between different ASNsand/or different core networks. The MIP-HA 584 may provide the WTRUs 502a, 502 b, and/or 502 c with access to packet-switched networks, such asthe Internet 510, to facilitate communications between the WTRUs 502 a,502 b, and/or 502 c and IP-enabled devices. The AAA server 586 may beresponsible for user authentication and for supporting user services.The gateway 588 may facilitate interworking with other networks. Forexample, the gateway 588 may provide the WTRUs 502 a, 502 b, and/or 502c with access to circuit-switched networks, such as the PSTN 508, tofacilitate communications between the WTRUs 502 a, 502 b, and/or 502 cand traditional land-line communications devices. In addition, thegateway 588 may provide the WTRUs 502 a, 502 b, and/or 502 c with accessto the networks 512, which may include other wired or wireless networksthat are owned and/or operated by other service providers.

Although not shown in FIG. 17E, it should, may, and/or will beappreciated that the RAN 505 may be connected to other ASNs and the corenetwork 509 may be connected to other core networks. The communicationlink between the RAN 505 the other ASNs may be defined as an R4reference point, which may include protocols for coordinating themobility of the WTRUs 502 a, 502 b, and/or 502 c between the RAN 505 andthe other ASNs. The communication link between the core network 509 andthe other core networks may be defined as an R5 reference, which mayinclude protocols for facilitating interworking between home corenetworks and visited core networks.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

1. A method for distributing media content among a group of cachedevices, the method comprising: monitoring content availabilityassociated with a content source; receiving content preferenceinformation and device property information associated with the group ofcache devices; determining, based on the content preference informationassociated with the group of cache devices, that a content objectavailable at the content source is relevant to at least one cache deviceof the group of cache devices; determining, based on scalabilityinformation associated with the content object, that the content objectcomprises a base layer and an enhancement layer that depends on the baselayer for decoding; selecting, based at least on the scalabilityinformation associated with the content object and the device propertyinformation associated with the group of cache devices, a first cachedevice from the group of cache devices for caching the base layer of thecontent object and a second cache device from the group of cache devicesfor caching the enhancement layer of the content object; andtransmitting instructions to the first cache device to cache the baselayer of the content object and to the second cache device to cache theenhancement layer of the content object.
 2. The method of claim 1,wherein the content preference information associated with the group ofcache devices comprises a viewing history of a cache device or asubscription to the content object associated with the cache device, andthe content object is determined to be relevant to the cache devicebased on a determination that the viewing history or the subscriptionindicates a preference for the content object.
 3. (canceled)
 4. Themethod of claim 1, wherein the scalability information associated withthe content object comprises respective resolutions or color gamuts ofthe base layer and the enhancement layer of the content object, thedevice property information indicates respective capabilities of thefirst and second cache devices for caching the base layer and theenhancement layer of the content object, the first cache device isselected based on a determination that the first cache device is capableof caching the base layer of the content object, and the second cachedevice is selected based on a determination that the second cache deviceis capable of caching the enhancement layer of the content object. 5.The method of claim 4, wherein the device property informationassociated with the group of cache devices comprises at least one of adisplay resolution, a storage size, an available network bandwidth, acaching history, a viewing habit, a decoding capability, or an accesspermission associated with the group of cache devices.
 6. The method ofclaim 1, wherein the group of cache devices comprises a home gateway anda plurality of end user devices capable of connecting to the homegateway and playing back the content object, where the contentpreference information associated with the group of cache devicescomprises respective content preferences of the plurality of end userdevices, wherein, on a condition that the content object meets thecontent preferences of at least two of the plurality of end user devicesand that the home gateway is capable of storing the base layer of thecontent object, the home gateway is selected for caching the base layerof the content object, and wherein, on a condition that one of the atleast two of the plurality of end user devices is capable of displayingand storing the enhancement layer of the content object, the one of theat least two of the plurality end user devices is selected for cachingthe enhancement layer of the content object.
 7. (canceled)
 8. The methodof claim 1, wherein the group of cache devices comprises a cache serveroutside a home network and a home device within the home network that iscapable of accessing the cache server, wherein the content preferenceinformation associated with the group of cache devices comprises acontent preference of the home device, and wherein: the home device isselected as the first cache device for caching the base layer of thecontent object on a condition that the content object meets the contentpreference of the home device, and that the home device is capable ofcaching the base layer of the content object; and the cache server isselected as the second cache device for caching the enhancement layer ofthe content object on a condition that the content object meets thecontent preference of the home device, and that the cache server iscapable of caching the enhancement layer of the content object. 9.(canceled)
 10. The method of claim 1, further comprising receivingaccess privilege information of the content object, wherein the firstcache device is selected for caching the base layer of the contentobject based further on a condition that the first cache device isauthorized, according to the access privilege information, to access thebase layer of the content object.
 11. The method of claim 1, whereinreceiving content preference information and device property informationassociated with the group of cache devices comprises discovering thegroup of cache devices via a device discovery protocol.
 12. The methodof claim 1, wherein the device property information associated with thegroup of cache devices comprises a viewing habit of the first cachedevice, and wherein the first cache device is selected for caching thebase layer of the content object based on an indication from the viewinghabit that the first cache device is used to view content outside a homenetwork at a frequency above a threshold value.
 13. The method of claim1, wherein the method is implemented on at least one of the first orsecond cache device.
 14. (canceled)
 15. A controller for distributingmedia content among a group of cache devices, comprising: a processorconfigured to: monitor content availability associated with a contentsource; receive content preference information and device propertyinformation associated with the group of cache devices; determine, basedon the content preference information associated with the group of cachedevices, that a content object available at the content source isrelevant to at least one cache device of the group of cache devices,wherein scalability information associated with the content sourceindicates that the content object comprises a base layer and anenhancement layer that depends on the base layer for decoding; select,based at least on the scalability information associated with thecontent object and the device property information associated with thegroup of cache devices, a first cache device from the group of cachedevices for caching the base layer of the content object and a secondcache device from the group of cache devices for caching the enhancementlayer of the content object; and transmit instructions to the firstcache device to cache the base layer of the content object and to thesecond cache device to cache the enhancement layer of the contentobject.
 16. The controller of claim 15, wherein the content preferenceinformation associated with the group of cache devices comprises aviewing history of a cache device or a subscription to the contentobject associated with the cache device, and the content object isdetermined to be relevant to the cache device based on a determinationthat the viewing history or the subscription indicates a preference forthe content object.
 17. (canceled)
 18. The controller of claim 15,wherein the scalability information associated with the content objectcomprises respective resolutions or color gamuts of the base layer andthe enhancement layer of the content object, the device propertyinformation indicates respective capabilities of the first and secondcache devices for caching the base layer and the enhancement layer ofthe content object, the first cache device is selected based on adetermination that the first cache device is capable of caching the baselayer the content object, and the second cache device is selected basedon a determination that the second cache device is capable of cachingthe enhancement layer of the content object.
 19. The controller of claim18, wherein the device property information associated with the group ofcache devices comprises at least one of a display resolution, a storagesize, an available network bandwidth, a caching history, a viewinghabit, a decoding capability, or an access permission associated withthe group of cache devices.
 20. The controller of claim 15, wherein thegroup of cache devices comprises a home gateway and a plurality of enduser devices capable of connecting to the home gateway and playing backthe content object, where the content preference information associatedwith the group of cache devices comprises respective content preferencesof the plurality of end user devices, and wherein the processor isconfigured to select the home gateway for caching the base layer of thecontent object based on a condition that the content object meets thecontent preferences of at least two of the plurality of end user devicesand that the home gateway is capable of storing the base layer of thecontent object, the processor further configured to select one of the atleast two of the plurality end user devices for caching the enhancementlayer of the content object based on a condition that the one of the atleast two of the plurality of end user devices is capable of displayingand storing the enhancement layer of the content object.
 21. (canceled)22. The controller of claim 15, wherein the group of cache devicescomprises a cache server outside a home network and a home device withinthe home network that is capable of accessing the cache server, whereinthe content preference information associated with the group of cachedevices comprises a content preference of the home device, and whereinthe processor is configured to: select the home device for caching thebase layer of the content object based on a condition that the contentobject meets the content preference of the home device and that the homedevice is capable of caching the base layer of the content object; andselect the cache server for caching the enhancement layer of the contentobject based on a condition that the content object meets the contentpreference of the home device and that the cache server is capable ofcaching the enhancement layer of the content object.
 23. The controllerof claim 22, wherein the home device comprises at least one of a homegateway or an end user device that is capable of decoding and displayingthe content object.
 24. The controller of claim 15, wherein theprocessor is further configured to receive access privilege informationof the content object, and to select the first cache device for cachingthe base layer of the content object based further on a condition thatthe first cache device is authorized, according to the access privilegeinformation, to access the base layer of the content object.
 25. Thecontroller of claim 15, wherein the processor being configured toreceive content preference information and device property informationassociated with the group of cache devices comprises the processor beingconfigured to discover the group of cache devices via a device discoveryprotocol.
 26. The controller of claim 15, wherein the device propertyinformation associated with the group of cache devices comprises aviewing habit of the first cache device, and wherein the processor isconfigured to select the first cache device for caching the base layerof the content object based on an indication from the viewing habit thatthe first cache device is used to view content outside a home network ata frequency above a threshold value.